Support

Only on your phone. Cykie never uploads it anywhere, so the developer can't see it either.

In Cykie, open Settings › Your data › Export to save a backup, then use Import on the new phone.

Allow notifications for Cykie in your phone's Settings, then use Settings › Notifications › Send test notification in the app.

The lock screen offers to erase the data on this phone and start fresh, since there's no account to recover it from. Restore a backup afterwards if you have one.

Cykie learns from the periods you log. Add your past periods (Insights › History › Add past period) and predictions get better with each cycle. You can also set your usual cycle and period length in Settings › Cycle and units.

Subscriptions are managed by Apple: open Settings on your iPhone, tap your name, then Subscriptions. Being a Supporter is a thank you. Every feature works the same with or without it.

No. Its predictions are estimates and aren't a reliable way to prevent pregnancy.