Quote - yes I undertand but I'm more talking about the main software used.

If you are using for example 3DSMax and Vray or any other package then you have received a license number from the vendor that is unique and assigned to your real name. This could be part of the information that is entered when submitting contributions to a contest.

This shouldn't be automatically checked but could be verified with the software vendor.

I'd never give over my serial key to anyone but the company who designed and released the program, or the company that bought that software company and took over it's support, IE: Jasc and Corel.

Handing out your serial key is asking for trouble.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi