How do I limit in-app product licence in one device

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licensing

Windows-Store

I am writing a Point-Of-Sale application for Windows Store (Windows 8.1). This is my intention: The application is free to install, but not fully functional; to use the app, users must buy an in-app product monthly.

My question is:

If a user, using one account, installed my application on many devices, and then bought the in-app product on one device, will that user be able to use my app on:

(1) Only the device she/he had made the purchase of the in-app product?

Or

(2) All device she/he has installed my application, using the same account?

I want to limit the users so that a user must purchase one in-app product for each device monthly.

Please help.

Thanks