I bought Neverwinter nights 2 yesterday and there is no cd key. any one cam help me?

With your browser, not through Galaxy.
Click the down arrow on NWN2, then View Downloads, then More, then Serial Keys.
See Pics:

Thanks! multiplayer is not working, do you know about it?

Sorry, I don't.
But if you post what you've tried and what is happening (or not happening) I'm sure someone here will be able to help you.

Thanks again!

Hi! I cannot find the cd keys either, and because the layout has changed, the tips i see on the forums are all outdated. Can someone help me too?

Point your mouse cursor on your nick at the top bar of your browser window, choose Games and find NWN2. Click on it and choose More. Now click on the Serial Keys as shown in this screenshot: https://www.gog.com/upload/forum/2019/06/058deb4a0fabb6165e302d0be62653656e862dcf.jpg. Here are your keys. :)

I navigated to the correct screen, but it says "serial keys exhausted."

How can I get one?!?! I want to play with a friend online

You won't be able to unless\until GOG gets some more keys.
They should at least warn you on the game page, if not stop selling the game until they get keys for it.

Ahh, yes, indubidibly.