Android How to protect downloaded content when canceling an in-app purchase?

Question

Android

Good time
I'm going to distribute my application through GooglePlay and would like to clarify a few points.
I'm still not fully versed in the technology of in-game purchases - and would like to get a little introductory advice - if possible.
Standard network RPG game with online ratings, interaction between users.
But the main game mode is a single passage.
There is a fully functional free client for Android.
The user registers his version of the client on the server (using a Google account or something else - it doesn't matter here) and gets access to the basic content.
Conventionally, the first 5 cards for the development of his character and adventures.
After mastering the basic locations, if the game is pleasant, the user buys access to new Maps.
The main value of the game is in these additional cards.
How to protect against the following scenario.
1.) the user buys/downloads Map_6 to his smartphone.
2.) conditionally copies the game along with access to the new map and the map itself to another (rooted) smartphone
3.) Uploads the assembly from 2. to free access, and when modifying the client, it gets the opportunity to play on unpurchased maps.
4.) Cancels the purchase by returning the spent money
5) We do 1-4 every time a new card is released, change them and enjoy all the delights for free
While there is the following implementation idea:
The map and all its resources are encoded with the user's key, and are generated interactively at the time of download from the server after purchase through the store.
We limit the number of canceled purchases from one account.
But such measures do not solve anything, but only prevent the use of cards from 2. on the official client

Answer 1

We bind purchases to the user, we do not allow the same user to log in from several different clients at the same time, we check whether the current user has bought what he is going to use.