It would really be cool if I could use this module to manage fees for my "Premium" modules.

Insert the module in a "Host" mode oin a site so administrators could manage subscriptions for premium modules.

Could anyone else use this feature?

I guess so. I would be a way to manage the payments for premium modules for all sites on a specific installation. But in the perfect world I as a host would be able to pick the modules and pricing I want per portal not globally. All clients are not equal in the amount of support required per module.