Yeah, you shouldn't need your product key since it's linked to your account. Mine was linked too, but I'm thinking I needed the product key anyway. That may be due to my clean install though.
Just check to see which version you have installed today before installing your new components. I didn't think to check it before I rebuilt, forgot what I had installed, and guessed (and guessed wrong). If you're doing a clean install, it doesn't hurt to install the wrong version. It's just time-consuming to wipe your drive and reinstall Windows if you get it wrong. Again, this would only be applicable if you decide to do a clean install on a new drive.
Before you do anything, be sure to download a fresh version of the Windows installer/repair software to a thumb drive. Having a downloaded version will save you time during install. DO NOT use an old version of the Windows installer/repair software as it won't have all updates, etc.