ask about free royalty texture

It depends. You have to look at the terms of use on each place where you aquire your textures. For your mentioned textures.com, look here: https://www.textures.com/terms-of-use.html Specifically 2.1c "You are permitted to: sell 3D models bundled with modified versions of the Photos (with the exception of Substance .sbsar files), but only if you add the following text to the documentation accompanying the model:
"One or more textures on this 3D model have been created with photographs from Textures.com. These photographs may not be redistributed by default; please visit www.textures.com for more information.""

P.S. you are aware that royalty free license ≠ free to use, are you?

ok thanks for answer, yes im aware

so in short i need to customized texture first before bundle it in my 3d package right.

sorry first time meddle with license agrement(never read it before) :D, usually i just click ok ok install :D haha