You don't need to have your product key to hand during installation.

If you've not installed Windows 10 before, you'll need a product key but you can enter this post-install as Windows 10 as a very limited trial, and require activation within 48 hours after install (don't worry, Windows 10 will prompt and remind you). Make sure your drive can burn a dual layer disc. If you choose to build a bootable install DVD, due to the size of Windows 10 (over 5GB), you'll need a blank dual layer DVD. Ideally you'll need a blank formatted USB stick before starting and we'd recommend using an 8GB stick as Windows 10 is over 5GB. If you choose to build an installer on a USB key, any existing data it contains will be overwritten. You'll need to either download the Windows 10 ISO and create your own USB or install DVD or ask a friend with a Windows 7 or 8 machine to use the Tool for you to create a bootable USB stick or DVD. It won't work on Windows XP or Vista PCs, even though these can be upgraded to Windows 10 using a fresh install. Please note, there are several points to remember when using the Windows 10 Media Creation Tool.

The good news is, if you use the Windows 10 Media Creation Tool to move up from Windows 7 or 8, you get to keep all your installed software, data, files and other settings. There are also options to create a bootable environment (a USB key or ISO file) for installing Windows 10 on another PC. You can use the package to install Windows 10 on the current PC, if it's running Windows 7 or 8.1, or reinstall Windows 10 on a system where you've already activated Windows 10. Windows 10 Media Creation Tool is a portable program which provides various ways to update an older PC to Windows 10 build 21H2 (November 2021 Update) or, if you're an existing Windows 10 user, get hold of the very latest version (November 2021 Update).

Creation tools win10