The History tab keeps a day-by-day record of your scans. You'll find it in the bottom navigation, next to Scan.
Browsing your history
Use the arrows on either side of the date, or tap the date itself to open a calendar and jump to a specific day. Each day shows the scans you completed, with the intention behind each one and the time it happened.
Viewing a scan
Tap any scan to see its full results.
No scans that day
If you haven't scanned on a particular day, you'll see "A quiet day" instead of a list. You can browse to another day or start a scan to add to your history.