On your device. Actuo is local-first: your plans, streaks, and progress never leave your phone, and no account is required. Deleting the app deletes its data.
Open the Premium screen and tap Restore purchases while signed in to the same App Store / Google Play account you bought with.
Subscriptions are managed by your store account, not by us: Settings → Manage subscription in the app, or your device's App Store / Google Play subscription settings. Cancelling stops future renewals; access continues until the period ends.
Check that notifications are allowed for Actuo in your device settings, and that a reminder time is set in the app under Settings.