If you have a product key for Windows 10 Pro, just enter the product key and it will change to Pro.
Click Start > Settings > Update & security > Activation > Change the product key then enter the new product key then click Next to
Activate
If you are unable to activate Windows 10 after all the above and you are certain you have the correct edition installed, then please attempt phone activation:
Activate Your Windows 10 License via Microsoft Chat Support