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The game keeps asking for a serial cd-key when i launch the game and i can't seem to find where this key is located in any of the options. Where can i locate thiskey for my Redemption GOG Copy? i tried searching everywhere in my library Redemption Settings or More options and i just can't seem to find this damn key... the game will launch but there will be this tiny screen asking for the serial key as soon as i launch the game. Any help is apreciated.

Using Latest Windows10.
Some people had the same problem, for example:

"There is not a serial key in that menu. According to the support, there is something wrong with my installation or the compatibility with my version of windows, not a missing key. I will attempt to check all that and correct the problem. "

Just reinstall the game and try it again.
Dang, i thought it was just me. I notices my Steam version contains a "RegisterGame.Bat" file, i think i could just use tht instead. GOG should provide a Register file or at the very least a Serial in order to avoid this issue.