Consider integrating your existing analytics provider into your Messenger Bot. Most analytics providers allow you to create server side events, these can then be used to measure retention, engagement, errors and other metrics that are important to your experience.
Once your app is live, see how your integration is performing by viewing the Messages tab in Page Insights. Be sure to keep your spam and block rates low by focusing on good user experiences.
You can export analytics data by navigating to App Analytics under Messenger. This is restricted to admins of the app.
Ratings and Reviews
People can leave a 5-star review and provide freeform feedback on your bot from the user control option: Manage > Leave Feedback. Feedback posted here will be emailed to you daily and is also available via the review dashboard in your app settings.