These scripts from MS will get you the last 5 digits of your product key. You can then use this information to get the reset of the product key from your Microsoft Account.

NOTE: This currently only works for Office 2010 and 2013. Note sure if it works with Office 2016.

In the administrative command prompt, type the following:

  • Office 2013 (32-bit) on a 32-bit version of Windows
    cscript "C:\Program Files\Microsoft Office\Office15\OSPP.VBS" /dstatus
  • Office 2013 (32-bit) on a 64-bit version of Windows
    cscript "C:\Program Files (x86)\Microsoft Office\Office15\OSPP.VBS" /dstatus
  • Office 2013 (64-bit) on a 64-bit version of Windows
    cscript "C:\Program Files\Microsoft Office\Office15\OSPP.VBS" /dstatus