If you lose premium access, here is how to get it back.
1: Open the in-app purchase view (For example by clicking on any item in the statistics tab)
2: Scroll to the bottom and press restore purchases.
This should resolve everything for you.
If you ever run into these types of issues, even if the steps above solve them, please let us know by sending a message through the in-app support system. If there is a bug in there, we want to fix it, so others won't get the same error ;)