If you have implemented Google's LVL in your paid Apps, then you must implement our licencing library for AndroidPIT (or alternatively remove Google' LVL because this would always return "not bought" due to the App being bought on AndroidPIT and not in Google Play). You can find documentation on how to do this here: http://www.androidpit.de/de/android/developer-licensing-howto. If you do not use Google LVL, then you do not need to use our licencing library.