Hi, I've looked again and again... if I go to https://store.uberent.com/Account/MyKeys, my key is listed, but there is no option at all to convert it to Steam... Has the procedure changed? Is it bugged? Both my team and uberent acconts are linked, but Steam still proposes me to buy the game, not install it...
Automatic key convert button was disabled for some reason. Though likely Uber support can help you: http://support.uberent.com/open.php
