Question on CoD:Ghost PS3 upgrade to PS4

[Qbert]

I have ghost for PS3 and upgraded to PS4 download version for 10 bucks.

Not crazy about it. My cousin wants to buy it off me....can he also upgrade to PS4 version for 10 bucks, or not because it was my game?

 

[DriedMangoes]

I believe once you used the code, it won't work anymore?

 

[TeKPhaN]

U don't need a code to play cod correct? I have it but don't remember lol.

 

[KongRudi]

If you bought the digital-version, you will find a PS4-version sitting on your PS4-store for 10 bucks.
If you bought the disk, I think you will need the code in the game-cover - to download a different upgrade version - while keeping the PS3-version inside your PS4.
PSN download-codes usually only work once and transfer the product to your purchase history, just as you bought it.
On the upgrades games in PSN-store, only Assasins Creed showed itself, because that's the only one I had bought digitally. :-/