Windows Key
Windows Key
You can set up the ISO right away and use Command Prompt to install it and activate your Windows key today.
They likely dropped it in Windows 8, and it was mandatory during installation. It might have been included in Windows 8.1 as well.
It looks like you're uncertain about the details, but I believe it's supported in Windows 7 and likely will work in later versions too. You should definitely be able to complete the setup without a license, even though there appears to be a recurring fullscreen prompt.
You can find the ISO for Windows 7 Home Premium by visiting Microsoft’s official website or authorized retailers.