Stuck, found a bug, or have an idea that would make Clefs better? We read everything.
We usually answer within one business day. Include your device, app version and what you were doing when the problem appeared: it helps a lot.
Open the paywall from any locked screen and tap Restore Purchases. Premium is a one-time purchase tied to your store account, so it follows you to every device signed in with it.
USB keyboards work out of the box through a compatible adapter. For Bluetooth keyboards, open Settings → MIDI in Clefs and pair from there: pairing in system Settings alone isn't enough. If notes still don't register, power-cycle the keyboard and reopen the exercise.
All ten: treble, bass, alto, tenor, soprano, mezzo-soprano, baritone (F and C), French violin and sub-bass. The guided course starts with treble and bass; every clef has its own practice and statistics.
No account, and everything works offline. Your progress is stored on your device.