Hi,
I found one of my image on a website and it's possible to download it at its original size (20mp) without watermark. Image is credited from Shuttestock. On Shutterstock website I try to find some information about the maximum size allowed for display on a website without success. I remember to have found it last year, did they remove the limitation and full size is now allowed  ?
Thank you

It used to read  "On web sites, provided that no Image is displayed at a resolution greater than 800 x 600 pixels;" from the 2011 Terms and Conditions here http://www.shutterstock.com/license?date=2011-05-05&type=standard

It all depends on the Terms of Service at the time of purchase, here are some more http://www.shutterstock.com/license-history
There must have been too many contributors winging about such infringements (I was one of them) causing them to get off their backsides to do something about it.  Reporting infringements and getting them to do anything was lengthy and time consuming process, I just gave up in the end.

If there is a date on the web page you could chase it up if the corresponding Terms of Service are in your favor, but only if you have nothing else useful to do.