What's is an unlock key for minecraft playstation 3?

That would be your license key. How the hell did you download minecraft for PS3 without getting a license key. A license to use it.

Now I'm not saying you did it but. What if you did download it from some warez site well. The console still requires your PERSONAL DIGITAL SIGNATURE to run it. So really if you download something from PSN you also download the license to use it.

At least it should be.

if you downloaded it from PSN and didn't get this key. Then try to redownload it.

Download the demo.simple as that. When you download the demo it will be unlocked to the full version

That is the key that unlocks the demo and makes it the full game, a lot of games have a demo and a key which is like the registration key for pc software.
you forgot the demo, there should have been a demo and an unlock

Where do I get the unlock key for minecraft ps3?

When I Download minecraft on my ps3 it wasn't on the game system

Thank you for the info