Just to reiterate - Not your keys, not your coins.
Always store your coins at a wallet address where you, AND ONLY YOU, have WRITTEN DOWN the seed words to access it. Don't store these digitally, computers can crash, or worse!
As mentioned before, wallets don't "store" coins, but act as a gateway to access these coins which are stored on the blockchain.
Good luck!
Did you not read the original post? He used to keep his coins externally at like Nicehash however now he installed the client for the ARRR Pirate coin and it sending his coins to his wallet on his computer. Since the wallet dat file is on his PC then he obviosly has access to his coins. So its "His coins because His keys".
Now I would advise that he makes a backup of this dat file at least incase there is a computer crash but other than some virus or malware they should be pretty safe. Much safer than leaving on Nicehash which was hacked a few years back.