You do realize that this is a gifting thread? The reason people are sometimes not using their freebie code is exactly this: to keep it as a gift because they don't want the game or already own it. You can always check GOG codes to see if they expre or not. So if they should expire "never" it should no problem to save them for a giveaway like this. I would not simply say "mistakes can be make" if GOG made this mistake at least three times now. If they want the codes to expire they should give out codes with an expire date. Makind a mistake again and again simply gives you a bad reputation and right so imo. I have to do correct work in my job as well and yes, I am allowed to do a mistake now and then but not every time!

That's the point.

And, please, note how the issue is solved. There should be some announcement - "hi, we just noticed that you've received wrong gift code - please note that it has been replaced by a code with expiration date" and later "hi, do you received our previous message? your code is unused and is about to expire - take care of it!".

Instead of that they're doing nothing and sending you replacement if you're crazy enough to check expiration date of never-expiring code regularly and raise a support ticket in case of negative result. Most of people are going to lost those codes and they'll never complain - and it seems to be perfectly fine for GOG!

If you look at the OP and see what this thread is for, you might begin to understand why.
This thing is a giveaway, and people are upset because they gave these codes to this giveaway with the understanding that these keys would not expire (as it has been in the past for things like Worms Forts Under Siege or LBA2 or other games). It ain't exactly the nicest feeling to be told that the expiration date of "never", which we're used to seeing from most giveaway keys before, is suddenly null and void and everyone's keys are expired without warning.
To be fair, it's only a minor annoyance since we're only talking freebies here, but the principle of the thing ain't too hot, not to mention, as has already been stated, they've screwed this up 3 times in a row (4, actually, if you count a similar incident I've been through recently) and you'd never notice unless you were paying close attention to the forum.
Sorry, pal. You've gotta have a bit more community participation in order to get anything from this giveaway. Hang around the forum a bit, have fun, join some conversations, get to know some folks!
Denied due to lack of participation.

Well, OK then. But, how many community participation is needed? Or what can I do to prove I'm worthy of that key? I'm not very communicative since my English is not so good.

No set value, but being eligible for this giveaway can be taken as a perk for being generally seen as a (reasonably) active community member.
About language, remember I think a few cases back when moon was managing it when a user was considered eligible for being active on some non-English forum (or non-English posts in game forums being taken into account). But since the content of the posts may not be understood, having that count would probably require quite a high level of activity, so it'll be immediately obvious on a quick search I guess.

Thank you for tips

It's a bit of a hard gauge to explain...there's really no set "amount" or whatever, the purpose is just to be visible enough that I can be sure the asker isn't some sort of scammer or alt account.
So far as the language problem, posting in the non-English forums counts as well.
I'll also sometimes accept donations of keys as "participation" since scammers don't exactly give games to the community (and if they try the sneaky attempt of giving away games they won from other giveaways, they're usually spotted rather quickly), although I want to make it clear that this is by no means is this some sort of "give one take one" giveaway, nor should you or anyone else feel obligated to donate anything. Just pointing out another method I use.

I have some spare keys I got earlier and could share with others (Mount & Blade, Fantasy General). But, since some one mentioned in this thread that this keys might be expired, I'm afraid I can't propose something in exchange for now. Don't want to make myself a scammer for real.

Free Fantasy General codes have expired unless you requested a replacement right away, in which case they're still valid until July 2. And according to posts, free Mount & Blade keys also expired, and don't think there was even a way to get a limited-time replacement for those once they did. But you can (and everyone really should!) check keys before attempting to give, of course.

I have checked both keys. They indeed has expired. And I think they expired soon after the promotion, and the expiration date wasn't mentioned at all.

*nods* They were listed as expiring "never", then GOG decided that was a mistake (that happened in 3 or 4 known cases so far...) and expired them all at once and silently, no notice or anything, see all the discussions about it...

deleted

I came to this thread, because it seemed it was a place to get Community Giveaways, and I thought I would see what was on offer. I was taken to the last post, and noticed a discussion, very similar to others I saw yesterday in other threads. Apologies if I misunderstood ... it is a big topic.

You and others might like to read the related reply by GoG representatives in another thread (second to last reply on page 1) -
https://www.gog.com/forum/general/gog_is_invalidating_gift_keys_wich_have_a_never_expire_limit/page1

Well, if you came to this thread because you thought you could get some Giveaways I still don't understand the reason of you asking why people should not redeem all their codes at once (because if people would redeem everything there would be no gifting). Anyway no apologys needed - I just wanted to explain the reason why this is not always the case.

I did read the "official" GOG answer (since it is only a support answer it is not that official and GOG unfortunately is not often seen here anymore), thank you for the link. "Official" GOG answer was

"No worries - and I again apologize for the misunderstanding. We're working on it - I cannot promise, however, when the "NEVER" displayed for the expirable codes will be fixed.
Have a great day!"

For me this simply sounds AGAIN like wrong prioritizing. They said something similar about the still not working notifivations for thr web sites. STOP trying to perfect Galaxy and START fixing this construction site you call a store, GOG. Please!

In addition to this I have totally lost my trust with GOG support after my latest experience with them. So until they really fixed something for me their promises aren't worth much atm. sorry. I loved them once and maybe will again sometime...

BTW: Please let us stop discussing this any further in this thread. I know zeogold is pretty lenient with OT discussions but I don't want to test his patence here :)