N.B. The screenshots and descriptions are for the iPhone/iPad version.

You can use this option to set up reminders when memberships for each horse comes up for renewal.
Tap on Stables -> Preferences from the home screen, to adjust the number of days warning Stable Manager gives you of the imminent expiry of your memberships.
If you have halted or paused this particular membership but don't want to delete it, you can mute imminent or overdue alerts by selecting 'Mute reminders' here for this membership only.
Federations such as the FEI require that their passports are re-validated every few years. The validation date is different to the renewal date. Leave 'Validation due date' off if this membership does not require validating.