[Stephen]

No your computer doesn't need to be licenced but by installing the OS whether its the preview or bought copy, you are licensing that computer and effectively agreeing to the T&Cs.

The EULA is you agreeing to abide their rules when you install their software. So in effect that then gives you permission to install and run that software.

Which means your PC then has a licence. When you buy Windows you are buying the software licence or key and whatever machine you install it on is then licensed to use that.

So in effect what you said is wrong.