Microsoft Office Professional Plus 2016 is a legitimate commercial product. It requires a genuine license purchased from Microsoft or an authorized reseller. Using the string you provided to activate Office would violate the software's EULA (End User License Agreement).
It offers a perpetual license. You pay once and own that version forever, without the "software as a service" monthly fees. swdvd5officeprofessionalplus2016w64english exclusive
It allows you to install Office on computers without an active internet connection. Microsoft Office Professional Plus 2016 is a legitimate