You should care about your images and that's all. You have no need to worry about the guy abusing the service with his 1M images, that's the owner of said service problem. As for confidence in service I can tell you I use it for at least 5 years and still can access those images. For a free service I'd say is quite good. I don't have earlier images since I discovered the site only 5 years ago so I can't speak for higher image retention time.