An unknown license appears in the Manage Product Keys interface in Tableau Desktop 2021.1. The license displays no Product Key or Product values but shows License Expires "12/30/1899" and Maintenance Expires "N/A".
Users may initially receive a "License Has Changed" pop-up stating "Tableau has detected that the license on your system has changed. You must restart Tableau for the license changes to take effect." After restarting, the mystery key appears in Manage Product Keys.
Attempting to refresh keys in this situation may result in a "Some of your product keys could not be synchronized" error in Tableau Desktop which includes a reference to a trial entitlement ID.