How to make an object disappearing forever after picking it once

Hi, I’m trying to find a way to make something like this in my game.
I do want to let the player trying to find 3 hidden objects in each level.
It works, but they appears again if you haven’t picked all of them from that level.
How do I can make an object disappearing forever even if you restart the scene (level)?

Could you please share the code you are using?. I think I might know what the problem is.



I’m using this code