In Sage 100c, select Library Master, Setup, System Configuration.  Click on the Registration tab.   Edit to change the product keys, then select Activate and/or Update.

Will have to take your word for it as our var ended up doing it.  Not sure I could have done it as I did not see a Product Key in all the emails I received, to enter on that screen.  Thanks for the help.

I think Sage goes and looks for new keys every 28 days anyway.  If you got prompted to pick a new user interface, Classic or Standard one day, that was it.

Help - About will tell you your version.