I must inform you that downloading copyrighted software without a valid license or permission from the software owner is not allowed and may be against the law.
You're looking for a free download of Artcam Pro 8.1, and you want to make sure it's verified. I understand that.
That being said, I'll provide you with some general information about Artcam Pro and possible alternatives.
Artcam Pro is a 3D modeling and CNC machining software developed by Aartbaan. It's widely used for creating complex 3D models, simulations, and generating G-code for CNC machines.