What happened::
He said he has office 365 keys (US, UK & UAE) region and I bought 3 keys for trial. All three keys are invalid and he provided replacement which were invalid too. Now he stopped responding.
Scammers Profile Link:
https://bitcointalk.org/index.php?action=profile;u=220719
Reference Link:

https://bitcointalk.org/index.php?topic=832514.new#new
Amount Scammed:
15 USD
Payment Method:
Bitcoin
Proof of Payment:
https://www.blockchain.com/btc/tx/d6ed93d2efa24bc9bc1bc27279bacb9616ebb6533954b9b045f2c87df6d34018
PM/Chat Logs:
https://imgur.com/a/E4yflae
Additional Notes:
Help me get refund as he doesn't have what I asked for and dealt for.