I think the best way is to sign in using your Microsoft account on this device. Then this Windows license will be automatically linked to your MS account (you can see the devices linked to your account at https://account.microsoft.com/devices).
Then if you reinstall the OS on the same device, just login using the same MS account and the windows will activate automatically showing you a message like “windows is activated using a digital license linked to your account”.
In some cases you do not even have to do what I said above and the windows will activate automatically on then same device. But just in case.
