If you purchase an upgrade license from the Home version to the Pro version on the Microsoft Store, that is a digital license linked to your Microsoft account.
Restart your PC (not shut down) to check if the upgrade to the Pro version is completed.
If the upgrade does not complete, please proceed with the upgrade using a generic Pro key using the following method.
Important - disconnect totally from the Internet
Open the Settings App (Gear icon on your Start Menu)
Go to Update and Security - Activation
Click Change Product key
Enter this generic product key: VK7JG-NPHTM-C97JM-9MPGT-3V66T
When prompted, click 'Activate Product'
If the above does not work first time, restart your PC and try again.
Note the generic key will cause the Home edition to upgrade to the Pro edition, then your own legal licence will activate automatically after you restart (not shut down) your PC