I'm blown away when I see a band playing a really long song with lots of changes and intricate melodies/harmonies and rhythm hits and stuff, but they're playing it without looking at any sheet music. Or Ill see somebody playing the entire "rite of spring" or something on piano without any music in front of them. Do you think being able to memorize long and intracite, detailed pieces of music is a skill that you can improve upon over time? Like can you sharpen your "musical memory" or whatever you want to call it? Does it just start to automatically  become easier to do the longer you've been playing?
it's really no harder than memorizing a paragraph full of words, in your native language