Implementing in-app billing / purchase in android app

The existing app displays information from a offline database. The app can be used free of charge as lite version.
Your task is to establish an in-app billing that the user can purchase the full version through an in-app billing. The purchase is only once necessary for the user.
Current idea of realization: In the lite version the database table "lite" is used and in the full version the database table "complete" is used. So after purchasing the full version only the variable of the database table is changed. Alternative ideas are welcome. After purchase, the app should work in offline mode, i. e. an online check if the full version has been purchased is not provided.