Yes, you can anytime upgrade Windows 10 Pro from Windows 10 home edition. You can apply that upgrade by making use of a spare key from an earlier edition is of windows, including Windows 7 Pro or Ultimate, Windows 8 Pro, or Windows 8.1 Pro.
The procedure is particularly useful while restoring Windows 10 on a system that originally shipped with Home edition and manually upgraded to pro. In this situation, you may need to utilize a generic product key first to upgrade to Pro. After the upgrade is completed, you can activate it by making use of the stored digital license or a product key.