I believe after you sign up for the beta, it overrides the app you are shown in the Google Play Store.
You can check the application version by going to settings->application settings->Mooshimeter. It should show you the version number. The beta is 22, the production release is 17.
The link again to sign up for the beta is here: https://play.google.com/apps/testing/com.mooshim.mooshimeter