If Esri Maps for Office is installed on the operating system but the Esri Maps tab does not display in Microsoft Excel, the add-in may be disabled.
When Microsoft Excel crashes, or changes are made to the operating system, the Esri Maps for Office Component Object Model add-in (COM Add-in) may be disabled or turned off in the process.
If Esri Maps for Office is already checked, or it is not in the 'COM Add-Ins' menu, it may have been disabled. Use the Manage drop-down menu and select 'Disabled Items'. Select 'Esri Maps for Office', click Enable, and restart Microsoft Excel.