xDrip » Features » Backup » Save database daily
This setting can be found under Settings −> Less common settings.
By default it is disabled. And the setting Glucose retention on the same page is also set to 0 by default.
With those (default) settings, your database will contain all your readings and will never be deleted.
So, why would you need to enable Save database daily?
If you suspect that something is wrong causing your database to be corrupted frequently, you can enable the setting so that you can receover an older version of your database if it is corrupted.
Under normal circumstances, this will not be necessary.
