The thumbs up option by quick-reply and quote for posts randomly disappears for me. It's kind of weird.

 

I believe you have five(?) uses per day, and the option disappears when you've run out.

You can either un-thumbs up a post to get one back, or wait til tomorrow.

 

OK, that might be it. I noticed it go out, then come back in a short period of time. But it looks like that happened near midnight for my set timezone.

Edit: Yeah that must be it. The option comes back when I remove one.

 

You can use ten thumbs up a day, and like Iztiak said after that you'll have to wait to get them back.

You also can't give thumbs up on a post that's more than two months old, and we recently changed the mafia forum to disable thumbs up, so that might be a source of confusion if you're used to it.