What's the big deal. Email CNC Software with your sim number and they will tell you if it's a legitimate sim. They will also ask you to relicense it, but at least you'll know that you weren't scammed by the ebay sale.
As for the "Codeshark" being easier....
A Piper Cub aeroplane is easier to learn to fly, than an F16 Fighter Jet. I'd still rather have an F16.
Mike Mattera
Tips For Manufacturing Training CD's, DVD's for Mastercam, SolidWorks, Inventor, G-Code Training & More
http://www.tipsforcadcam.com