To check which app version or build you have, and whether you are using the App Store or Testflight version, first exit the event if you're in one.
Get to the list of events, and touch the user profile icon near the top:
Scroll down in that popover to get to the bottom, where the version number, iOS version, and more information is displayed:
In this screenshot the version of the app is 1.56.5, and the build number is 922.
If you see App Store, this means you downloaded the app from the App Store.
If you see standalone, this means you downloaded the Mac app from our website (not the App Store)
If you see TestFlight, this means you're using the TestFlight version of the app; to go back to the App Store version just install over top of your existing app from the App Store app.
The long series of digits at the bottom is your Device ID in case support asks for it.