I bought this Chinese Writer app, I found it amazing and entertaining. However after I purchased and opened my new app, after one game it changed back to limited use. Like I didn't buy anything.
The purchase was done trough a store (Google Play / Apple app store). can you please check your account with the store? could it be that the purchase was cancelled or did not went trough? It may also be that Google/Apple still want to verify something for the usage. Can you check that you have Internet access when you start the game?
In general the handling of the purchase is made by/trough Apple/Google. We have very limited possibilities to check anything there.