Surviving Mars also has - in my case - no less than 3 serial keys.
One that appears to be for the base game, one for the Deluxe Edition Upgrade Pack and one for the First Colony Bonus.

Hell if I know what those are for exactly though. Maybe something related to Paradox resp. their stupid Paradox Account bullshit accessible from the main menu?

Factorio have auto-gen serial number in GOG Library.

For Europa Universalis III , serial key is no more provided , i contacted the support and it''s accurate.
Reason : The game doesn't require one; only Europa Universalis: Rome Gold & For The Glory: A Europa Universalis Game have one provided.

Hm, either that or the typical Paradox forum registration for the shiny icons and avatars. Thanks for the info.
Ah, right, I have forgotten about that one. Thanks for the reminder!
Did you buy the game recently? When you say that a serial is no longer provided, do you mean that there is not even a "Serial Key" selection in the drop-down menu? Or there is one, but it is empty?

Not recently, i think there was one attached to this game originaly. (however i'm not certain).

But i contacted the support (the french one) , and they said no serial key was required (maybe originaly it was only for the'"Paradox version", you could get : since it's a DRM free version, it should be worthless to get one there. I could mistaken...that's my feelings; i could be wrong)

II have no serial attached to it atm, or no more if it was the case before...(pick your choice)

Someone else shcould be able to confrim there is no more serial key attached

i could post a screenshot if you want.

ps : fixed typos

I can confirm this.
I bought
Europa Universalis III Complete
and
Europa Universalis III: Collection Upgrade
at Nov 3, 2016.

I always download newly bought game immediately, and record any serial keys I got.
For the game, it is something like XX0X-00x0-xxx0-0000-0000-0xx0.
(X for upper case, x for lower case, 0 for numbers)

gogrepo.py also save a !serial.txt for me.

The SERIAL KEYS section is gone from the game now.

My brain is still working properly then :P

Also,since i have a copy on steam there are 2 keys attached

one for EUIII Heir to the Throne
one for EUIII: Divine WInd

Thanks for the confirmation. In that case, I will remove the game from the list/mix.

Tales of Maj'Eyal: Forbidden Cults have auto-gen serial key in GOG Library.

Considering the presence of serials in the other two expansions, I expected that to be the case, but still, thanks for the confirmation.

Most definitely a bug.

Are you saying I miss a key? I also have gaun pledge dlc key for deadfire.

I'm saying that the key is not supposed to be for a random game.

I'm not only one who got the key for extra game. It was around the time people were getting POE in piñatas.