I think you provide a really great service, but you're also competing against a lot of other services out there. If they need ads to survive, you probably will too. From my perspective, if people want free, they don't care about ads. If they want a paid account, they can go that route too. My suggestion would be to do what you need to do to get enough money to make this worth your time which includes ads. At the same time, offer a subscription plan for users who want it. I do hope it works out, because I think your platform is one of the best out there.... but if I needed to, I would use another service because, ultimately, this space has been commoditized, and it's mostly a secondary concern for just "putting my images somewhere so I can publish my blog post."