...
If you have been inactive for a period of time, you will be logged out.
This auto-logout time can be changed by going to Tools & Settings > Manage User > Choose user > Account > Login Timeout
...
You should not rely on this to log you out however.
To ensure that you have logged out correctly, select the red off symbol on the top right of any WOL page and then close your browser.
You may also be logged out or 'kicked' off Wise Owl Legal if there is an update going on.
You will be informed of any times that you would be unable to use WOL during these updates.