Can not run game because I have no License String ...The mentioned option like : Profile - Games - Din's Curse - More does not exist in my GOG Interface.. Simply can not find it ..
Thanks for any help.
TTT

Not your profile; as the notice on the store page says, visit your game library via website (meaning: in a regular browser, not Galaxy), open the game tile, and click the "More" dropdown. Do you not have a "Serial Keys" entry in that menu?

AFAIK, this is the case for any and all serial keys that might come with GOG games -- whether the code's for multiplayer authentication, or for a copy of some extra game. I think most of the non-game goodie packs are only accessible (or, at least, only downloadable) in library via a normal browser, as well.