No it doesn't. It requires ownership of the game, and there are several ways to achieve it.
Auto-update and in some cases multiplayer, I guess.

PS: from the Grim Dawn game card: So I guess it's about multiplayer.

Grim Dawn must be registered to your GOG account in order for you to be able to play multiplayer through Galaxy - this is why it's asking for a code. Whoever gifted the game to you should have given you a gift code to redeem to your GOG account; if they didn't then your copy of the game isn't legit.

Ah I hadn't seen the Grim Dawn part, just a lot of weird convoluted messages about mysterious online features and gifted games.
In that case duh.
I would love to know how it got gifted though.
Just so I don't gift games to my friends the same way.
If I had friends.

WHICH MEANS I AM ONLINE WITH GALAXY Cannot post to GOG.COM with Galaxy without being online with it. And The fact that I've posted every message on here through Galaxy, nullifies everything you just said.

BTW I DO OWN THE GAME Perhaps you and this other douche bag are purposely going out of your way to pick a fight by saying really retarded things on purpose even though you know better.

How retarded do you people seriously have to be, to continue saying "You don't own the game" AFTER you were told at least 3 times that I do own the game. It's fucking retarded to keep telling people what they do and do not own according to them.

ONCE AGAIN I OWN THE GAME
So now you and others can stop mentioning/hinting saying I don't any more in any reply for ANY REASON.

No one was picking a fight with you, just trying to ascertain why you may see that message.
Ask support to check the validity of your "Gift" give them as much detail as possible.

Spelling edit...fecking hands.

Do you own the game with this account? Is the game still in your library? Because if a gog employee says that it's not, we do tend to believe them.
And before you snap again, do double check if it is in your library. Sometimes codes bought from grey markets do get revoked, so while you may have redeemed it and installed it normally, it may no longer be in your library.

The problem is that it seems liike it is not registered to your account, which I keep telling you. You need to contact support, dig out the recipe you got via email when you added the game, and let them sort it out. That's all you need to do and it will work as intended.
Aye, the key may have been revoked.... didn't think of that, I assumed some sort of data base misshap

Okay, have to say this...why should anyone help you, when you're being rude and obnoxious?

I'll say this one last time for the mentally challenged (This includes staff being just as stupid) A game doesn't have to be on ones library in order to LEGALLY own it. If a game has been paid for then the person owns it..PLAIN AND SIMPLE.

Trying to make up all these stupid ass lame excuses such as it's not in someone's library or any of this other nonsense is just sheer idiotic.

So before you say "Before you snap again" how about you double check how often you and others were stupid towards them FIRST. If someone says they own something, then don't fucking argue with them and keep saying they don't just to piss them off, then complain they snapped at you.

This all sounds like sourcery to me!

Nope. That isn't how it works. I can pay amok to buy a car, but if amok doesn't have the right to sell me the car, or doesn't give me the proper paperwork, I do not legally own said car. The proper paperwork in this case is the game being in your library.
So, again, is the game in your library? If yes, you can use Galaxy's features. If not, you cannot use Galaxy's features.

P.S. Feel free to ask any lawyer if paying for something is enough to legally own that item.

P.P.S. According to you, you were gifted the game. Thus you didn't pay money for it, thus (according to you) you do not own the game.

LOL, in order to get the game working with Galaxy you have to own it on GOG. Plain and simple. When you own it here, it shows up in your library. Plain and simple. Since it doesn't, you don't own it here and can't use Galaxy for multiplayer. Plain and simple.

And I'm slowly losing my patience. You might ask yourself who the mentally challenged person really is - one tip: he has a temper problem...

Speak for yourself. It's not our fault you choose to be ignorant. Staff members can see what games you own, so calling them stupid just makes you look, well, stupid.

If you so clearly "own the game" then what was the deal with you posting about "PERSON 1" "PERSON 2" "PERSON 3" etc?

It seems to me (and pretty much everyone else here) that this code you speak of:
1) Was not redeemed on your account which you are accessing now, but a different one. OR
2) Was redeemed by you, (which allowed you to install it) but was later revoked because it was originally bought with a stolen credit card.

The latter is very common with codes not bought on GoG but from resellers like G2A or Kinguin where they have a problem with people buying game codes with stolen credit cards and reselling them for real cash before the fraud is discovered.

From all appearances so far, you do not CURRENTLY have the game on the account you are accessing Galaxy with and it does not appear to be an issue with Galaxy.

If you go to the "Account" tab with your user name, go down to "Library", does the game show up there? Is there an entry for it on the "Orders & Settings" tab?

Also, calling people stupid or retarded is not a good way to get help for your problem...

Edit: And if you think owning the game allows you to install it but then give the game code away to someone else, you are sadly mistaken. That would be piracy.