If you have changed your smartphone or copy all your apps to another device, then the BookBeat app can have a hard time following after. In that case you might get the message that your subscription is inactive even if it is active. It can even happen that you get this message by mistake if you have recently reactivated your subscription.
Most of the time you can fix this by restarting your app. If this doesn't work then press "Log out" under "Profile" in your app and log in again. After that your BookBeat account should work as usual.
If you haven't copied your apps or gotten a new phone and restarting or logging out does not work, then please check the date and time on your phone. You can get an "inactive subscription" message if you have changed the time and date on your phone.