On iOS, 1SE can notify you when you have a Rewind: snippets from the past to look back on.
You can get it once a week, or every day you have a Rewind.
Turn on Rewind notifications
Tap Profile > Settings > Notifications.
Turn on Rewinds.
Tap Notification preferences to customize how often it triggers. Select Rewind Weekly to trigger it once a week, or Every day I have a Rewind available! if you want a daily notification when content is available.
You'll get a notification whenever there's something to look back on. If nothing arrives, check that notifications are allowed for 1SE in your phone's own Settings.
To add snippets from a Rewind, see How to Use 1SE Rewind.