There are settings in the Data Exchange that will log an employee off after a given amount of time after their rostered shift has ended, assuming that they have forgotten to clock out.
A typical setup is 4 hours after the end of a rostered shift (e.g. an employee was rostered to end work at 3pm therefore at 7pm they would be auto logged off), and 12 hours after the start of a non-rostered shift (e.g. and employee starts work at 10am but isn't rostered, therefore they would be auto logged off at 10pm).
These settings and more can be determined within the Data Exchange task. If you are an administrator, you can learn more about the set up at How do I configure the Auto-Logoff Data Exchange?