How To Enable A Disabled Add-on In Internet Explorer
All add-on management operations are done in the Manage Add-ons window. In order to open it, press the Tools button (the one that looks like a wheel) on the top-right side of the Internet Explorer 11 window. Then, click or tap the Manage add-ons button.
Now, go to the LogmeOnce add-on and find it, click or tap on Enable.
Then follow as shown: