Not Sure Membership is the correct solution

I am not sure if I am trying to put a round peg in the square hole.

I have a mobile app builder system that I am launching and it is $99/mo per app the client builds

So I am not sure how to manage the multiples.

and if the build App-A which creates the initial membership, then later build App-B and App-C, we need to add an additional $99 added to the monthly bill.

if the customer cancels App-A leaving B, C active I want to make sure the login still works.

My brain hurts.