How to determine the instance when the user logged out or the session has terminated?

[Michail]

It is necessary to trigger some clean-up services once the user logs out of his/hers session.

[PaiChung]

There aren't any great ways to monitor this.

You could monitor people that are in session and then exit the session

you can track if your clean up ran properly or not by tying your logout to the running of it.

this way if people idle out or close the browser, you can pick up those and run clean up for them.