Download macos high sierra dmg on windows. Microsoft Office 2016 Product Key for Professional Plus. Microsoft Office 2016 Pro Plus Full Version Serial Key Unlock The World Download. The Microsoft 2016 Office ‘s security key is normally a single 25-digit character code key. Note: The steps to install the 2016 or 2013 versions of Office Professional Plus, Office Standard, or a stand-alone app such as Word or Project might be different if you got Office through one of the following: Microsoft HUP: If you bought Office for personal use through your company, see Install Office through HUP. Office 2016 product key is also stored in the system registry file after installation.