This guy is selling hacked and keys obtained via illegal methods. Some keys will stop working.
Most of his keys can be found much cheaper at other websites, just do a search. These keys are available at least by 50% cheaper elsewhere.
http://www.mpgh.net/forum/
http://www.g2a.com
http://www.dhgate.com
Do a search on the above websites and you can find the windows and antivirus keys that he is selling at much lower prices.
Do not get ripoff by this guy. I have visited all the above three links and IMP kapitashoka is the real deal of all 4.