How does the Membership plugin bill people?


I am thinking that it's pretty obvious that the Membership plugin would bill people on a regular basis for their subscriptions, however obvious or not, I can find nothing whatsoever that tells me how the recurring billing takes place.

So I'll ask the question.. does it somehow send out invoice emails each period to the customers?

If not, what happens to keep people paying their subscriptions?

This is not addressed anywhere as best I can see, but it a vital part of a membership system. Perhaps I'm just blind and have missed it?