EndNote tab persistently disappears
If your EndNote tab on the Word ribbon persistently disappears this could be due to the load behaviour within the registry settings.
Load Behaviour:
If the EndNote disappears every time word is opened it could be down to the registry setting. This is a Microsoft issue and not a problem with EndNote per se.
Under Add-ins in Word you will see the current load behaviour of the particular add-in. The load behaviour of the add-in should be set to "Load at Startup".

If the load behaviour is "Unloaded" then you can change the behaviour for this setting:
- On Start menu and type "regedit".
- In the Registry, go to HKEY_CURRENT_USER > Software > Microsoft > Office > Word > Addins >EndNote.WordAddin.Connect.
- The Load Behaviour will be set to 0 or 1 or 3.

If the Load Behaviour is set to something other than "3" do the following:
- Close Word down completely.
- Open the Registry Editor again as in previous point 2.
- Change the Load Behaviour to "3." Close the Registry Editor.
- Re-open the Registry Editor to confirm "3" is still the chosen value.
- Open Word. The add-in should now be visible every time you open word.