Repair the registry using - https://www.tweaking.com/content/page/windows_repair_all_in_one.html
Art was receiving the Microsoft Office cannot verify the license for this product, even though the software said it was activated.
Looks like this a known issue when you have Office 2016 installed and Windows upgrades to the latest version. There is a chance where it'll break inside the registry and make it seem like the software isn't validated. I repaired the registry, using tweaking repair tool. I confirmed the message has disappeared in Outlook, Excel, Word.
I'll create a knowledgebase for the Support Desk incase we start seeing more of these.
IT Support Center
Mount Saint Mary College
Newburgh, NY 12550