The Windows activation is part of the installation process but has nothing to do with the Product Key. When you start the installation process, that's when it prompts you for a Product Key. After the installation process, then the activation software kicks in which is performed over the Internet or by phoning a call centre. You cannot use Windows without completing the activation.
I don't know of any 30 trial period without a Product Key. As far as I know, you either buy a licensed copy of Windows or you don't.