I'm not sure but what I've read is that they keep part of the fee that usually goes toward rewards or points in other cards. I don't mind this at all because I think they are providing an amazing and much needed service that I've been wanting for years. Their apps and web extensions are also great. Last time I had to cancel a card because some website got hacked it took me weeks to resolve and change it everywhere I needed. I would happily pay let them have all of the rewards to not go through that again. Sorry if I sound like a shill, I swear I have no relationship with them. I just really like the service.