The primary reason that most of us “forget” something is that we never really learned that something in the first place…
“Memorization” is in quotes because the goal of studying is not to memorize a piece of music like you memorize a sequence of random numbers…
The real goal is to understand a piece intimately… by tapping into all aspects of the music: sight, sound, thought, action, and emotion… thus absorbing its patterns and essence into your eyes, ears, brain, muscles, heart, and soul.
I struggled greatly with “memorization”… until I realized that my problem was not “memorization” at all. The problem was that I never truly learned the piece in the first place. And I didn’t truly learn it because I never truly studied it. This is true for all of us with “memory” problems.
The cure for a “memory problem” is not to practice “memorizing”, but to study-practice more effectively. In other words, if you want to remember something… make it memorable!