What happens when someone subscribes in the app store?

When a subscriber pays through the app stores we create a connected subscriber in Leaky Paywall with a random “unipress” username/password. This lets you manage their access to content in the apps. 

Google/Apple do not release any information about app store subscribers. The subscriber would need to submit their email/username/password in the app which would update their Leaky Paywall subscription info and give them access to your website content.