I downloaded the infinity grass package, I bought materials from it, it is close to 20, but when I transfer the materials to my own file, when I delete the grass package, the materials become colorless, so how do I prevent this?
You have to migrate the textures along with the materials.
The paths inside of the textures probably still point to the grass package directory.
I transfer them all, then move the materials to my own file and delete the rest, but the materials are colorless.