Confirmation on how affiliate and pro sites work

Hi, Just setting up affiliates and pro sites together and want to confirm that I have the logic correct.

I've enabled the pro-site add on for affiliate, and set the 1, 3 and 12 month prices.

Am I correct in saying that affiliates will acrue these payments as long as the referred users keep paying?

ie, when someone referred by an affiliate stops to be a paying pro-site member the plugin works this out and stops paying monthly?

Also is there anyway to have the affiliate plug do a one off payment at the start and not ongoing? Or does it just not work like that?