Day One stores metadata for each entry. This includes location, date/time, activity, music, etc.
Accessing Entry Info/metadata in Day One on iOS
Tap the More (•••) button at the top right of an entry, then Entry Info.
Tap the Map at the bottom of an entry.
The metadata page includes details like:
Shortcut to On This Day
Entry Creation Device
Options to share/export, view PDF, and view Plain Text