I warned @Dan about @Thunder, and reported about him but I don't think there's something done to him since I didn't get any responses from Dan. I want to warn sellers here.
In short, he bought a license off me then nulled the item and uploaded on some sites. Then he came back to me showing his innocents (he was banned from logging into the license client area) and threaten me of PayPal dispute and I actually stupidly refunded him. I only gained evidences that he did the above after refunding him. I sent him a message asking him to return me my money which as expected he ignored me. I lost both license and money.