If you activated a free upgrade to Windows 10 or bought and activated Windows 10 from the Microsoft Store, you have a digital license for your device. This means you can reinstall the same edition of Windows 10 that your device has a digital license for without entering a product key. During reinstallation, if you’re asked to enter a product key, you can skip this step. Windows 10 will automatically activate online after the installation is complete.
source: https://support.microsoft.com/en-us/help/12440/windows-10-activation
Does MS digital license 'fingerprint' hardware information during the free upgrade / activation and store it (at Microsoft) , so that the next re-install queries MS for the fingerprint and activates Windows 10?
Thought the disk drive may change, I expect that none of the other fingerprinted hardware will change.