Before trying anything else, simply restart the app. Purchases are automatically checked on start up when using an android phone. If this fails, continue on.
If you are having issues with purchases not applying on Android devices, try the below process.
Log out of the RISK app via the in-game settings and restart the app. All you stats will be retained.
Check what Google Play Services account is associated with the RISK app in your OS settings. Make sure this is the one you purchased the RISK premium unlock etc.
Open up the RISK app and log in again.
If you still have issues, send us a support ticket with your google play order number.
For information on how to find your order number, see the below link.