Office 365 Activation Keeps Reverting to Professional 2019

I searched online for plenty of methods and uninstalled Office many times, but nothing worked. After repeatedly uninstalling, reinstalling, and restarting, I finally went back to the seller I bought the license key from. Their method worked on the first try.
The cause was a previous license activation or cracked activation of microsoft office 2019, which left the licensing in a confused state.
I'm sharing the method here and keeping a record for myself.
Here is the OSPP command activation method:

1. Enter cmd in the search box, then right-click and run as administrator
2. Enter cd C:\Program Files\Microsoft Office\Office16 and press Enter. If you get an incorrect path message, enter cd C:\Program Files (x86)\Microsoft Office\Office16 and press Enter
3. Then enter: cscript ospp.vbs /dstatus and press Enter
4. You may see a five-character key suffix on your computer. Next, enter: cscript ospp.vbs /unpkey:KHGM9 (replace the key suffix after the colon with the five characters shown on your computer). Press the enter key to remove that key, then repeat for any other keys
5. Finally, enter: cscript ospp.vbs /act and press Enter 6.After you see the message confirming successful removal, right-click word installed on your computer and select “Run as administrator”, then sign back in to the Microsoft account associated with office to activate it