Merit is not buy and sell. Merit is like in your post. So you will improve your post quality for the great merit. If not, get merit your account rank won't increase. So you will improve your post then you get a merit. People will be like your post, then people will be sending the merit your account, Then account rank also increase. People know the marination before using. If need information who will send your account, check your profile the check the merit link. Then you will get some information.