We recently had an office that needed their Microsoft Office 2016 re-installed. They had 20 downloadable copies but we had no idea which license was being used by which employee. Using the following method we were able to find the product keys and get their licenses straightened out.

https://support.office.com/en-us/article/Change-your-Office-product-key-d78cf8f7-239e-4649-b726-3a8d2ceb8c81#ID0EABAAA=Use_a_command-line_script

Let us know if this helped you…