The methods given above are the options to directly change the product key in your Office 2016 / 2019 application. 2 little programs: licence backup.exe xentry start. So if your keep loosing licence authorisation this should work for you. They copy licence file into safe location, and replace them just before xentry will start.
Navigate to Office installation folder by running this command:Ĭd C:\Program Files\Microsoft Office\Office16