A similar question was already asked here, but wasn't answered. I'm developing iOS application for service that already has its own account system on their website. With your account you can subscribe for premium service to get additional features like high quality videos etc.
I'm trying to implement same functionality in iOS application. If user purchases subsription it has to be connected to his account in the system, not to his Apple ID. And if he logs out and authorizes with another account he cannot use subscription benefits and has to purchase another subscription for second account.
Can I implement this using in-app purchases?