Thanks! I was aware of the limited use license and I guess these licenses differ from service to service. My biggest question was in the exclusivity. I guess I was mistaken by thinking that you more or less give away your rights on your photo there by giving one service exclusive rights.

I know some photographers that use services like Zenfolio and have options to buy the full rights for a photo(sometimes for as little as 50 bucks). I guess you could choose if you want to have this option in stock-services? I think big companies like Ikea for example would want exclusive rights for an image they would like to sell on canvas. This would mean you as the photographer would sell all your rights and you could not even print one for yourself anymore.