won a full released game, but the key said the game is for beta testing?

Chances are that yes, you shouldn't mark as received. However, could you give us the title of the game? That would help.

It seems a key provided by the devs http://www.steamgifts.com/archive/search?q=Onion+Force

some games are listed as beta,yet they are the full version of the game.

Most beta testing keys are equivalent to normal keys (only difference being that the developer provided the key to the person for free)
*If it is in your library without the word - beta behind.

The only time I've ever been scammed here on SG trades is by someone that traded beta keys that this person said would be full keys on the games launch but at the official launch of this game the beta keys were invalidated. Also there are at least 5 other SG users that I know about that were scammed in the very same way and by the very same serial beta key scammer.

So not every beta key becomes a full game key but some are invalidated/removed after a games official release.

If your beta key becomes invalidated or is removed from your games list mark the game as not received.

This is quite common. The key here Is that it says "xxx for beta testing". This generally means it's the full game, if it said "xxx Beta" then it might not be.

The "for beta testing" keys are those that the developer has generated before the games official release, usually devs will generate a few thousand keys before release to meet the demands of YouTubers, streamers, reviewers and promotional giveaways.