To make Travel Reasons mandatory for your employee's trips, simply go to the ‘Payment’ tab of the Admin Panel and then to ‘Trip settings’. In ‘Required booking info‘, tick the box ‘Reason for trip‘ to enable this setting.
After that, employees will be unable to book on the company account without entering a reference, thus preventing unauthorised journeys. The Travel reason can also be a free field to be filled in directly by passengers on their app.