In-App Subscriptions with multiple products

Hello, We have an issue when we trying to develop in-app purchases.

One user or organization can register an unlimited number of websites in our App. They should have a subscription for every website they register with. A user can only have one subscription from a Subscription Group while using an in-app subscription service. In this situation, we are even unable to use Subscription Groups to offer the subscriptions since we don't know how many sites user going to register before hand. For ex: with our organization there can be about 200 websites.

How it possible to use in-app subscriptions in this case?

Thank you

In-App Subscriptions with multiple products
 
 
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