The Activity Log is a timeline of past monitoring with audio recordings assigned to their respective timestamps. It is always stored in the Parent Station within the app's cache.
During the monitoring, you can access the current Activity Log from the Parent Station quickly with one of these 2 ways. If the baby is sleeping, there always appears this text: Last noise 2 minutes ago. If you tap on the underlined time value, the current Activity log will open.
Another option is through the menu on the Parent Station (Menu -> Activity log).
You can access all past Activity Logs from the main menu by tapping on the icon of a clock inside a circular arrow. From there you can also delete past logs if you want to.