First, you have to practice listening to music. You have to focus on everything: melody, rhythm, harmony, instrumentation, and dynamics. You also need to study

First, you have to practice listening to music. You have to focus on everything: melody, rhythm, harmony, instrumentation, and dynamics. You also need to study those things so you know exactly what you're listening to. Practice scales, arpegios, and chord progressions and you'll start to recognize them. If you hear a song in a key that you can't even play in, it doesn't matter how good your musical memory is. I started playing piano as an adult and can read music and play by ear. I worked as a dueling piano player for a few years wherr listening to your partner and figuring out what they're playing is a part of the job. I also write music down in various forms. Chords and lyrics, guitar tabs, and sheet music. Everything helps, but you have to practice playing by ear as well. Just put a song on a loop and play along until you get it right.