> that Apple wouldn't have an API that allows locking app functionally behind licenses; This is what their subscription system does, though. I'm not familiar w

> that Apple wouldn't have an API that allows locking app functionally behind licenses; This is what their subscription system does, though. I'm not familiar with their for-pay app setup, but for subscriptions you can monitor the receipt and see what it's status is. Perhaps you can't do it from there, but I know when even an free app is installed, you still get receipt information written to the device.