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Most issues are resolved by fully quitting the app and reopening it. If that does not help, restart your device. Also check that the silent-mode switch is off and the volume is up.

All purchases and refunds are handled by Apple, not by the developer — we are unable to process refunds ourselves. Please request a refund from Apple at reportaproblem.apple.com.

All three options unlock the full keyboard and keyboard scrolling; all features are free on the 25 keys from C3 to C5 without a time limit. The monthly and annual plans renew automatically, and eligible new subscribers may receive a 7-day free trial. The one-time purchase (¥1,200 on the Japan App Store) is charged once, never renews, and has no free trial.

Open Settings on your iPhone/iPad → tap your name → Subscriptions → Harmodus Piano → Cancel. You can also use "Manage Subscription" inside the app's Settings. After canceling, you keep access until the end of the current billing period. If you bought the one-time purchase, there is no subscription and nothing to cancel.

Tap "Restore Purchases" on the purchase screen or in the app's Settings. This works for both the subscriptions and the one-time purchase. Make sure the device is signed in with the same Apple Account you used for the original purchase.

The free trial lasts 7 days and applies to the monthly and annual plans only. Billing starts automatically when the trial ends, unless you cancel at least 24 hours before it ends (see "How do I cancel my subscription?" above). The one-time purchase has no free trial.

Check the cable or adapter connection, then open the app's Settings → MIDI and tap "Refresh". Connected devices appear in that list.