rpm is free, and stays free. Supporting it costs 15 € / $15 a month and lifts the two limits that exist, because they are the two things that cost real money to run.
Nothing is deleted. Everything already in the cloud stays in the cloud and keeps playing; what stops is sending new music up beyond the free 100 GB. Your files on your own computers are never touched by any of this.
Checkout is not open. Write to support@rpmrpmrpm.com and we will tell you the day it is.