I am concerned about this. My experience is companies that switch to a paid service, do not last long after the switch.
Redroller being one of them. They died in 08 and went to chapter 11. Its usually a last ditch effort to save oneself.
When your free for so many years, users feel betrayed after the switch to a paid service.
With the fees users may look at other similar services like Vendio whose pricing now seems better.