On the company page it states:
It’s worth nothing that connecting your Steam and GOG accounts is permanent – you can only have one Steam account per GOG Connect, and if you delete the game on Steam (or refund it), they have the right to remove it from your GOG account as well.
There are benefits to this. Should you lose your Steam account – or maybe your games – you have a sort of fail safe, and you don’t need to repurchase all your games. It’s a decent system, and should be a welcome addition for most gamers.
However the games are available on the site only for a limited time, which is not exactly promising. But if you’re lucky enough to find your game there, then you can get a copy on GOG.com for life.
GOG.com has had an interesting history on the internet thus far, and most gamers have their respect for giving them good old nostalgic games to play without worrying about copyright. But only time will tell if this newest venture will be worth their time.