I made the mistake of purchasing a yearly subscription after trying the free lessons (one key at a time).
This app has a fatal flaw where it wont recognize the lower notes for more than 2 keys at a time. For just 3 keys (chords), it works about 75% of the time, and when adding a 4th note (bass root), it fails to recognize the lowest bass note, or the chord root.
This happens 100% of the time, making you get stuck and unable to progress. Worst of all, it negatively impacts learning chords and this is the worst thing to happen to beginners. Dont fell into the same trap I did. This software is deceptive advertising.
Jaybraham about Simply Piano: Learn Piano Fast