Anybody here ? who has been used in app billing in your app ? please

i want to add in my app ads removal system .if user purchase my app then for one month ads will not be shown .if user did not buy my app then ads will be shown .please help how to do it

My suggestion
If user buys,I hope you may enabled registration, store his name/user ID/email in firebase. Whenever app open or completed purchase make firebase to check up any of these detail present or not. If his anyone of detail matches make as mob visible false if not make it true

but this is not legal when i use extension for purchase .