I have been running Window 7 Ultimate without issue - it was a clean install and I am also running Office 2013 Pro. Plus also a clean install -  however, after the upgrade to Windows 10 - I am being told that the license key is not valid for this version.  I have uninstall office and reinstalled and I am getting teh same message -

any ideas?

The irony is that this is the only application that did not work after the upgrade.

thanksfor any help

Michael