Sadly, I got a notice from Google that the unlockers for Asphalt 5, 6, and 7 are removed from Google Play. I have asked for the reasons for removal, but I haven't got a reply yet, so I don't know when (if ever) these unlockers will be republished.
To the best of my knowledge there is nothing illegal about these unlockers, and I do think they are in line with Google's Terms of Service. If I am proven wrong, then I will of course remove all unlockers from Google Play.
My only reason for making unlockers is to provide people with a tool to help them get through difficult parts of games, for which they already paid. In my personal experience I've encountered several times that an update of a game resulted in corrupted progress files, so I had to start these games all over again. Also, if I want to play legally acquired games on two or more different devices, I always have to start again from scratch. To remedy these annoyances I made the unlockers as well.