diff --git a/services/web/app/views/project/editor/review-panel.pug b/services/web/app/views/project/editor/review-panel.pug
index 2db347f6a2..f6ac53f4cb 100644
--- a/services/web/app/views/project/editor/review-panel.pug
+++ b/services/web/app/views/project/editor/review-panel.pug
@@ -583,13 +583,13 @@ script(type="text/ng-template", id="trackChangesUpgradeModalTemplate")
 			div(ng-show="user.allowedFreeTrial" ng-controller="FreeTrialModalController")
 				a.btn.btn-success(
 					href
-					ng-click="startFreeTrial('real-time-track-changes')"
+					ng-click="startFreeTrial('track-changes')"
 					ng-show="project.owner._id == user.id"
 				) #{translate("try_it_for_free")}
 			div(ng-show="!user.allowedFreeTrial" ng-controller="UpgradeModalController")
 				a.btn.btn-success(
 					href
-					ng-click="upgradePlan('projectMembers')"
+					ng-click="upgradePlan('project-sharing')"
 					ng-show="project.owner._id == user.id"
 				) #{translate("upgrade")}
 			p(ng-show="project.owner._id != user.id"): strong #{translate("please_ask_the_project_owner_to_upgrade_to_track_changes")}
diff --git a/services/web/frontend/js/features/share-project-modal/components/add-collaborators-upgrade.js b/services/web/frontend/js/features/share-project-modal/components/add-collaborators-upgrade.js
index 5ea142854b..08c35f6b3d 100644
--- a/services/web/frontend/js/features/share-project-modal/components/add-collaborators-upgrade.js
+++ b/services/web/frontend/js/features/share-project-modal/components/add-collaborators-upgrade.js
@@ -64,13 +64,13 @@ export default function AddCollaboratorsUpgrade() {
           <StartFreeTrialButton
             buttonStyle="success"
             setStartedFreeTrial={setStartedFreeTrial}
-            source="projectMembers"
+            source="project-sharing"
           />
         ) : (
           <Button
             bsStyle="success"
             onClick={() => {
-              upgradePlan('projectMembers')
+              upgradePlan('project-sharing')
               setStartedFreeTrial(true)
             }}
           >
diff --git a/services/web/frontend/js/ide/history/HistoryV2Manager.js b/services/web/frontend/js/ide/history/HistoryV2Manager.js
index 833bda490c..d4c803db0e 100644
--- a/services/web/frontend/js/ide/history/HistoryV2Manager.js
+++ b/services/web/frontend/js/ide/history/HistoryV2Manager.js
@@ -35,6 +35,7 @@ import './components/historyLabelsList'
 import './components/historyLabel'
 import './components/historyFileTree'
 import './components/historyFileEntity'
+import { paywallPrompt } from '../../../../frontend/js/main/account-upgrade'
 let HistoryManager
 
 export default HistoryManager = (function () {
@@ -939,6 +940,7 @@ export default HistoryManager = (function () {
               'editor-click-feature',
               'history'
             )
+            paywallPrompt('history')
           }
           break
         }
diff --git a/services/web/frontend/js/ide/pdf/controllers/PdfController.js b/services/web/frontend/js/ide/pdf/controllers/PdfController.js
index 3ee971ae3a..d1843c562a 100644
--- a/services/web/frontend/js/ide/pdf/controllers/PdfController.js
+++ b/services/web/frontend/js/ide/pdf/controllers/PdfController.js
@@ -441,6 +441,7 @@ App.controller(
             'editor-click-feature',
             'compile-timeout'
           )
+          eventTracking.sendMB('compile-timeout-paywall-prompt')
         }
       } else if (response.status === 'terminated') {
         $scope.pdf.view = 'errors'
diff --git a/services/web/frontend/js/ide/review-panel/controllers/ReviewPanelController.js b/services/web/frontend/js/ide/review-panel/controllers/ReviewPanelController.js
index b15bddc62a..fe22fd4eb0 100644
--- a/services/web/frontend/js/ide/review-panel/controllers/ReviewPanelController.js
+++ b/services/web/frontend/js/ide/review-panel/controllers/ReviewPanelController.js
@@ -917,6 +917,7 @@ export default App.controller(
         'editor-click-feature',
         'real-time-track-changes'
       )
+      eventTracking.sendMB('track-changes-paywall-prompt')
     }
 
     const _setUserTCState = function (userId, newValue, isLocal) {
diff --git a/services/web/frontend/js/infrastructure/event-tracking.js b/services/web/frontend/js/infrastructure/event-tracking.js
index a9529ac91c..efd67c51cc 100644
--- a/services/web/frontend/js/infrastructure/event-tracking.js
+++ b/services/web/frontend/js/infrastructure/event-tracking.js
@@ -1,4 +1,7 @@
 import { postJSON } from './fetch-json'
+import sessionStorage from '../infrastructure/session-storage'
+
+const CACHE_KEY = 'mbEvents'
 
 export function send(category, action, label, value) {
   if (typeof window.ga === 'function') {
@@ -6,10 +9,29 @@ export function send(category, action, label, value) {
   }
 }
 
-export function sendMB(key, body = {}) {
-  postJSON(`/event/${key}`, { body, keepalive: true }).catch(() => {
-    // ignore errors
-  })
+export function sendMB(key, segmentation = {}) {
+  postJSON(`/event/${key}`, { body: segmentation, keepalive: true }).catch(
+    () => {
+      // ignore errors
+    }
+  )
+}
+
+export function sendMBOnce(key, segmentation = {}) {
+  let eventCache = sessionStorage.getItem(CACHE_KEY)
+
+  // Initialize as an empy object if the event cache is still empty.
+  if (eventCache == null) {
+    eventCache = {}
+    sessionStorage.setItem(CACHE_KEY, eventCache)
+  }
+
+  const isEventInCache = eventCache[key] || false
+  if (!isEventInCache) {
+    eventCache[key] = true
+    sessionStorage.setItem(CACHE_KEY, eventCache)
+    sendMB(key, segmentation)
+  }
 }
 
 export function sendMBSampled(key, body = {}, rate = 0.01) {
diff --git a/services/web/frontend/js/infrastructure/session-storage.js b/services/web/frontend/js/infrastructure/session-storage.js
new file mode 100644
index 0000000000..59accfb121
--- /dev/null
+++ b/services/web/frontend/js/infrastructure/session-storage.js
@@ -0,0 +1,45 @@
+/**
+ * sessionStorage can throw browser exceptions, for example if it is full.
+ * We don't use sessionStorage for anything critical, so in that case just fail gracefully.
+ */
+
+/**
+ * Catch, log and otherwise ignore errors.
+ *
+ * @param {function} fn sessionStorage function to call
+ * @param {string?} key Key passed to the sessionStorage function (if any)
+ * @param {any?} value Value passed to the sessionStorage function (if any)
+ */
+const callSafe = function (fn, key, value) {
+  try {
+    return fn(key, value)
+  } catch (e) {
+    console.error('sessionStorage exception', e)
+    return null
+  }
+}
+
+const getItem = function (key) {
+  return JSON.parse(sessionStorage.getItem(key))
+}
+
+const setItem = function (key, value) {
+  sessionStorage.setItem(key, JSON.stringify(value))
+}
+
+const clear = function () {
+  sessionStorage.clear()
+}
+
+const removeItem = function (key) {
+  return sessionStorage.removeItem(key)
+}
+
+const customSessionStorage = {
+  getItem: key => callSafe(getItem, key),
+  setItem: (key, value) => callSafe(setItem, key, value),
+  clear: () => callSafe(clear),
+  removeItem: key => callSafe(removeItem, key),
+}
+
+export default customSessionStorage
diff --git a/services/web/frontend/js/main/account-upgrade-angular.js b/services/web/frontend/js/main/account-upgrade-angular.js
index 3a3c94a786..c8e4f85b2d 100644
--- a/services/web/frontend/js/main/account-upgrade-angular.js
+++ b/services/web/frontend/js/main/account-upgrade-angular.js
@@ -1,13 +1,14 @@
 import App from '../base'
-import { startFreeTrial, upgradePlan } from './account-upgrade'
+import { startFreeTrial, upgradePlan, paywallPrompt } from './account-upgrade'
 
-App.controller('FreeTrialModalController', function ($scope, eventTracking) {
+App.controller('FreeTrialModalController', function ($scope) {
   $scope.buttonClass = 'btn-primary'
   $scope.startFreeTrial = (source, version) =>
-    startFreeTrial(source, version, $scope, eventTracking)
+    startFreeTrial(source, version, $scope)
+  $scope.paywallPrompt = source => paywallPrompt(source)
 })
 
-App.controller('UpgradeModalController', function ($scope, eventTracking) {
+App.controller('UpgradeModalController', function ($scope) {
   $scope.buttonClass = 'btn-primary'
   $scope.upgradePlan = source => upgradePlan(source, $scope)
 })
diff --git a/services/web/frontend/js/main/account-upgrade.js b/services/web/frontend/js/main/account-upgrade.js
index 5b66dff9af..e74b88a1c6 100644
--- a/services/web/frontend/js/main/account-upgrade.js
+++ b/services/web/frontend/js/main/account-upgrade.js
@@ -1,4 +1,6 @@
-function startFreeTrial(source, version, $scope, eventTracking) {
+import * as eventTracking from '../infrastructure/event-tracking'
+
+function startFreeTrial(source, version, $scope) {
   const plan = 'collaborator_free_trial_7_days'
 
   const w = window.open()
@@ -7,6 +9,8 @@ function startFreeTrial(source, version, $scope, eventTracking) {
     if (typeof ga === 'function') {
       ga('send', 'event', 'subscription-funnel', 'upgraded-free-trial', source)
     }
+    eventTracking.sendMB(`${source}-paywall-click`)
+
     url = `/user/subscription/new?planCode=${plan}&ssp=true`
     url = `${url}&itm_campaign=${source}`
     if (version) {
@@ -17,10 +21,6 @@ function startFreeTrial(source, version, $scope, eventTracking) {
       $scope.startedFreeTrial = true
     }
 
-    if (eventTracking) {
-      eventTracking.sendMB('subscription-start-trial', { source, plan })
-    }
-
     w.location = url
   }
 
@@ -45,4 +45,8 @@ function upgradePlan(source, $scope) {
   go()
 }
 
-export { startFreeTrial, upgradePlan }
+function paywallPrompt(source) {
+  eventTracking.sendMB(`${source}-paywall-prompt`)
+}
+
+export { startFreeTrial, upgradePlan, paywallPrompt }
diff --git a/services/web/frontend/js/modules/sessionStorage.js b/services/web/frontend/js/modules/sessionStorage.js
index c25d302ac7..532c3e179b 100644
--- a/services/web/frontend/js/modules/sessionStorage.js
+++ b/services/web/frontend/js/modules/sessionStorage.js
@@ -1,15 +1,17 @@
-angular
-  .module('sessionStorage', [])
-  .value('sessionStorage', function (...args) {
-    /*
-    sessionStorage can throw browser exceptions, for example if it is full
-    We don't use sessionStorage for anything critical, on in that case just
-    fail gracefully.
-  */
-    try {
-      return $.sessionStorage(...args)
-    } catch (e) {
-      console.error('sessionStorage exception', e)
-      return null
-    }
-  })
+angular.module('sessionStorage', []).value('sessionStorage', sessionStorage)
+
+/*
+  sessionStorage can throw browser exceptions, for example if it is full
+  We don't use sessionStorage for anything critical, on in that case just
+  fail gracefully.
+*/
+function sessionStorage(...args) {
+  try {
+    return $.sessionStorage(...args)
+  } catch (e) {
+    console.error('sessionStorage exception', e)
+    return null
+  }
+}
+
+export default sessionStorage
diff --git a/services/web/frontend/js/shared/components/start-free-trial-button.js b/services/web/frontend/js/shared/components/start-free-trial-button.js
index b110e8272c..4ff2e35312 100644
--- a/services/web/frontend/js/shared/components/start-free-trial-button.js
+++ b/services/web/frontend/js/shared/components/start-free-trial-button.js
@@ -1,4 +1,4 @@
-import React, { useCallback } from 'react'
+import React, { useCallback, useEffect } from 'react'
 import { useTranslation } from 'react-i18next'
 import { Button } from 'react-bootstrap'
 import PropTypes from 'prop-types'
@@ -13,25 +13,23 @@ export default function StartFreeTrialButton({
 }) {
   const { t } = useTranslation()
 
+  useEffect(() => {
+    eventTracking.sendMB(`${source}-paywall-prompt`)
+  }, [source])
+
   const handleClick = useCallback(
     event => {
       event.preventDefault()
 
       eventTracking.send('subscription-funnel', 'upgraded-free-trial', source)
-
-      const planCode = 'collaborator_free_trial_7_days'
-
-      eventTracking.sendMB('subscription-start-trial', {
-        source,
-        plan: planCode,
-      })
+      eventTracking.sendMB(`${source}-paywall-click`)
 
       if (setStartedFreeTrial) {
         setStartedFreeTrial(true)
       }
 
       const params = new URLSearchParams({
-        planCode,
+        planCode: 'collaborator_free_trial_7_days',
         ssp: 'true',
         itm_campaign: source,
       })
diff --git a/services/web/test/frontend/features/share-project-modal/components/share-project-modal.test.js b/services/web/test/frontend/features/share-project-modal/components/share-project-modal.test.js
index 51263e7b34..c6fe61b342 100644
--- a/services/web/test/frontend/features/share-project-modal/components/share-project-modal.test.js
+++ b/services/web/test/frontend/features/share-project-modal/components/share-project-modal.test.js
@@ -639,6 +639,8 @@ describe('<ShareProjectModal/>', function () {
   })
 
   it('displays a message when the collaborator limit is reached', async function () {
+    fetchMock.post('/event/project-sharing-paywall-prompt', {})
+
     renderWithEditorContext(
       <ShareProjectModal
         {...modalProps}
diff --git a/services/web/test/karma/ide/history/HistoryV2ManagerTests.js b/services/web/test/karma/ide/history/HistoryV2ManagerTests.js
index bf5a595bac..fc79175b7a 100644
--- a/services/web/test/karma/ide/history/HistoryV2ManagerTests.js
+++ b/services/web/test/karma/ide/history/HistoryV2ManagerTests.js
@@ -157,11 +157,15 @@ export default describe('HistoryV2Manager', function () {
         $http: $http,
         $filter: $filter,
       }
+      this.eventTracking = {
+        sendMB: () => {},
+      }
       this.localStorage = sinon.stub().returns(null)
       this.historyManager = new HistoryV2Manager(
         this.ide,
         this.$scope,
-        this.localStorage
+        this.localStorage,
+        this.eventTracking
       )
       done()
     })