Edit:
Why would they advertise something as lacking which apparently isn't needed?
(the only complaints over missing CD keys seem to come from people who want to play outside Galaxy)

for two reasons: cd keys are needed to play with people on other platforms, and there was no GOG galaxy multiplayer option at the time

One way or another: Ranting here on the forum won't get you anywhere.

You really move the goalposts here, dude.
First it's Battlefront 1 which you bought over a decade ago (despite it only being released here in 2019).
Then it's Battlefront 2 which you bought over a decade ago (despite it only being released here in 2015).
Now it's "the game got removed from my account without a refund"...

It doesn't. Not anymore - that's the point.
If the game got actually removed from your account in 2015 and you didn't get an reimbursement for it (btw: did you buy it here on GOG or somewhere else, because it was cheaper there?)...you should have contacted a lawyer back in 2015.
No matter what happened, or not happened - by now there is no legal ground for you to stand upon.

To find a serial key, you need to be logged in using a web browser. In your library, click the game in question, then the More menu. You should see Serial keys as a menu item there. If it's missing, open a support ticket.

You have 30 days from the date of purchase to request a refund. If you requested a refund in time and it wasn't handled, open a support ticket.

How is the goalpost moved? Are you disputing that I purchased it at all? And who contacts a lawyer over 5 dollars? Rainer Winkler, is that you?

An who opens a thread about $5 they lost when they bought a game 8 years ago??? Get over it.

Well, I do. Because I won't give more money to people who stole from me, but if they were to give me my money back I would be interested in using the platform.

What is that screenshot supposed to show me?

That the servers for the game have been taken down prior to your purchase and that you don't need a CD-key for LAN?

I wonder what makes one create a thread to complain about 5,- that allegedly (!) have never been reimbursed...eight (8) years after the fact?

Even if you still had a legal right to that reimbursement after all these years (you don't), your demand of getting paid back taxes and interests on these 5,- would get you kicked out of every court in the country.

Maybe you'd even get indicted yourself, for trying to fraudulent appropriate undue benefits.

Because that's exactly what judges hear, if you tell 'em that you knew 8 years ago already, that someone withheld a sum of money from you...but you then waited eight years only to demand reimbursement above the original sum (your tax and interest demands).

Edit:
Careful...somebody could see that as some sort of extortion.
The laws are fun stuff...

I don't have any serial keys either - for neither of the two games since as stated correctly in the mail, there is no legacy online support.
However, BF2 offers online multiplayer via Galaxy.

Even if the OP did get serial keys, he could not use them, because there is nothing to use them on. Downloading the games from "another site" won't change that.

You guys have blatant reading comprehension problems.
In the OP, I state clearly: "I ended up having to download it from somewhere else and use a keygen to play with my friends"
Obviously I am saying that the GOG representative in the screenshot I provided is wrong. Which they were: third party services at the time, which facilitated multiplayer in the wake of official servers being shut down, required unique CD keys to be able to play together.
Anyway, if you guys want to white knight for thieves, that is fine. I will continue not spending money on GOG.

GOG is not responsible for third party services. The people running the unofficial servers could have done it in a way that does not require a serial key, but they decided to keep those for whatever reason.
The official servers were already shut down. GOG got the games from Disney, they don't have servers and see (rightfully) no reason to provide keys. Talk about comprehension problems ...

But if you think you have been robbed, you should definitly sue them and end this tragedy.

Double-check your wallet funds. Other than that, only support can help you.

You are saying that the representative is lying or is wrong. Interesting

But as far as I know until the patched version Steam/Galaxy crossplay version (2 oct 2017) the game did not offer online multiplayer but LAN. So no CDkey was available for the GOG version.

What you want is a refund 8 years later plus interests as an act of good will and a CDKey that never was available to use it in a different version?

Indeed it is an interesting tale :D