iOS Question In-App purchase how to keep track of execution

you want to disable the purchase after 10 app starts?

i want to have people buy 10 runs on the app...then sell them some more runs.

just work with a counter the you decrement to 0.

you can set the counter back to 10 at successfull purchase.

not sure if this is allowed by apple tho since it's not really an in-app consumable but targets full app usage.
Might need to be the subscription type of purchase but I don't know if B4i supports this already as I never tested it.

You can use keychain to track the numbers which will not be affected even if the app is deleted.