have some keys want to give them, but don't know if they expired or not !!! what should i do ?

you know what? was thinking about leveling up but meh !!! i will drop them there

or like how I did it with the whitelist recruitment ;)

about 6 ?

because I'm quite sure keys don't expire.

most*
some free keys do, though they should not even be in the list to make a giveaway for.

alternatively you could just use them to bump threads (your own or others) =)

GreenManGaming has an official policy of dropping support for keys after a week from purchase, and has been known to invalidate keys after a couple of months.

IndieGala is known for the occasional "dead" key, and their support is less than stellar in the best of times- wait too long there, and they most certainly won't help you.

None of the other sites should give you any problems as far as dead keys go, though it is worth noting that even Humble doesn't extend their support for issues after "years" of leaving your keys sitting unused. So even though sites like Humble are making strong efforts to fix bundle issues, it's still best to try and not leave keys sitting around for that long, unused.

In the future, you may want to consider an alternative approach, unless you really don't care what happens to the keys. That thread is known for being filled with bots and ungrateful users, and has a negative reputation in that regard. There are several other threads dedicated to giving away keys (through more controlled means), and you can always do your own forum events for them [for example, asking forum users to post if they want the game, and then using https://www.random.org/ to determine a winner for the key], or key-drop them inside your giveaways.

Moreover, if the only concern is that the keys are expired, then there are plenty of people who would be willing to join and give you an 'Agree to Cancel' if necessary. It is worth noting that yes, you will lose your slots in that instance- but you can gain new ones easily enough, so it's worth just holding on to the keys a bit longer if you're especially unsure of them.

Basically, don't feel pressured to "throw your keys away", just because some users say you should, and because there's a risk of people being entitled and disrespectful by refusing to keep their promise to agree to cancel. Typically the users on this site will have your back, and at the very least, there's ways to give your keys away that are more likely to gain you openly expressed gratitude than the orphan keys thread will.