Assetbank will automatically log a user out of their account if they have been inactive for a certain period of time. The default value for this is 45 minutes.
If you're hosted with us, please get in touch and we'll be happy to change it for you.
If you're hosted on your own server infrastructure, you can edit the session timeout value in [tomcat home]/asset-bank/WEB-INF/web.xml
Save web.xml then restart apache tomcat to action the change.