In the ThisWorkbook module of the workbook (not the addin) enter something like this:
Private Sub Workbook_Activate()
Application.AddIns("MyAddin").Installed = True
End Sub
Private Sub Workbook_Deactivate()
Application.AddIns("MyAddin").Installed = False
End Sub
The word "Installed" is a bit misleading, as it only indicates whether the addin is checked or unchecked in the Addins Menu.
If by chance the ribbon is only for one workbook you should just attach the ribbon to that workbook.
If the ribbon is for multiple workbooks, people generally take the opposite approach to what you are doing, i.e., create an addin that uses application-level events to turn menus on or off when specific workbooks (or workbooks with a specific characteristics) are activated or deactivated.