Like every web app, wayahead uses a session to store when you log in and when you were last active. Sessions can't be kept alive forever, so every now and again you will need to log in again. When your session expires, you might see a code=39 or code=40 in the URL of the login page.
Your session stays active as you refresh pages or move between reports. It ends in these cases:
You have been inactive for 5 days. You will need to log in again.
You use biometric authentication and have been inactive for 24 hours. You can get back in with your fingerprint or face recognition. If you cancel, you can log in with your password instead.
It has been 45 days since you last logged in with your password. This applies even if you use wayahead every day.