With Touch or Face ID enabled you can lock your Billdu app. Enable the Touch or Face ID lock under Settings - Security and choose a Lock Timer. The app will lock itself if you don't use it for a set time interval or if woken up from a sleep mode. Face ID works only with iOS devices.
Billdu web app will automatically perform a logout after 30 minutes of inactivity. This is a security precaution in case you leave your browser without logging out - after half an hour you will be automatically logged out. To log in again a password will be required.
Please be aware that the process of creating an invoice or estimate without saving for more than 30 minutes is NOT considered as an activity. You should save your documents regularly.