Your keys are lost, however and I hope I wont be banned for telling you this - the original cd keys are not verified anymore.
So, if you have a legal NWN copy on your desk, you don't have to feel ashamed for using a cdkey from, ehm, certain illegal cdkey generators. I know many peoples are using those even when they have original cdkeys just for the ability to run nwn twice (useful for PWs).
Note, some persistant worlds (PWs) are checking the CDKeys for the security reasons, and if you use CDKeys from the source I mentioned there is a chance that your CDKey will be used already by someone else. This is only problem on the PW itself, if you intent to play single player modules or LAN, you won't have a problem with that...
Also, not sure whether this would be legal or not but someone might give you the CDKey that comes with NWN distribution from GOG. Because each distro comes with this specific CDKey and players who bought the game has to request new keys. You won't do that, just use the generic GOG keys to install game. However I do not have GOG NWN so I cant help you with that, neither I use CDKeys from generator so I cant give you link for my first suggestion...
