We’ve experienced some issues with this Lite-Version In-App purchase to Full Version concerning Google/Apple Accounts.
In case of payment failure, Google (Play Store) / Apple (App Store) declined your money transfer. We have nothing to do with payment of the apps, that’s why we also can’t say why it was declined.
The solution for this is a gift card for App Store / Play Store, which you can get at drug stores etc. Then it’ll always work.