On your Mac. With Notelit Pro and iCloud Sync enabled, also in your personal iCloud — never on our servers.
Settings → Pro → Restore Purchase, or from the upgrade screen.
Subscriptions are managed by Apple: App Store app → your account → Subscriptions → Notelit Pro.
Check Recently Deleted in the sidebar. Notes stay there until you delete them permanently.
Email vernongxq@gmail.com — we usually reply within 2 business days.