If you have a user who always has to re-enable the Outlook Addin every time they open Outlook in order to use it. This addin resiliency registry setting may be the key to your issues.
Instructions in this article discuss how to set that key-
Often times this is the fix when combined with the resiliency key above-
Look in the registry and set the Load Behavior key to 3 in these two places
1. Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\EIOBoard Outlook Addin 2010
2. Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\Addins\EIOBoard Outlook Addin 2010
Here are some additional troubleshooting guides for the Outlook add-in