Starting tomorrow music is illegal, except for one song per person. What's your song?

Just break the law. You've not stated what the sentence is and it doesn't sound very enforceable

Baby shark
Then I can still torture my enemies
- Big “you’re trapped in here with me” energy

Killing in the Name - Rage Against The Machine
And, then continue to listen whatever I want.

Are other people allowed to hear our song when we play it? If so, I choose Macarena and then sell my attendance at parties and weddings and so on.
- Big business brain

Is it illegal for me to hear any other person's song? Can we co-ordinate? I think with the 8 billion of us we have around we might actually get close to covering the full library of human songs as long as none of us repeats. In that case then I don't really care which one, I'm happy to be just assigned one to make none of us doubles up. Another question would be how well the human birth rate can keep up with number of new songs people come up with. If we can average out the rate of growth can we just assign any given new song to a registry so we don't exceed that average and that mete out a new entry from the backlog in the registry to each person as they're born? Maybe if we can assign a song to each person that has ever lived or at least who's life was recorded we can add some resilience to account for unexpected low birth yields or something. I'm assuming a song is still "legal" after its person has died. If not it'll be a bit more complicated.

If it'd never get old,
The Cranberries - Zombie
However, for a track that wouldn't get old for me very quickly
VØJ, Narvent - Memory Reboot

This is the Song that Doesn't End -Lambchops Play Along
- This was my first thought, played endlessly in the vacinity of the idiots banning music.

Jethro Tull - Thick as a Brick. I've always loved this song, it has a mix of different styles, from flute-forward chill sections to more classic rock sounding parts.
Oh and it's over 43 minutes long. Before anyone says "oh but there's part 1 and part 2", this was a limitation of vinyl and not the artistic intent behind the piece. It's one song, fight me.

When has something being illegal stopped anything?
🏴‍☠️
(Pink Floyd - either Time or Another Brick In The Wall)

John Cage - 4'33"
I think if I had only one song, I'd pretty quickly come to hate it. Although props to the commenter who said baby shark. Torture your enemies and become loved by children.

The 11 minute version of heard it through the grapevine cover by ccr where they just jam the hell out for the last half of the song
Or any instrumental by northlane. I like his vocals too but the instrumental just feels so good
Edit: Or maybe for longevity go with somrthing like the blue danube waltz or requiem in d minor

Dream Theater - A Change of Seasons. Because I want to make sure it lasts.
Alternatively, Six Degrees of Inner Turbulence, as that's technically one song.

Tori Amos - Yes, Anastasia
- Used to have a good buddy who was really into tori amos and could play a lot of her songs. Hope hes doing alright.

Aurora - Different Kind of Human
Mostly because it resonates so strongly with me, lyrically, and the song itself is so beautiful and timeless

Against me - The ocean.
The intense longing and driving song that is about becoming who you are hits extra hard when you know the singer has now come out as trans and is singing about her true self.

Phoria - saving us a riot
My comfort song :)
Also it's very relaxing and I think that's a good thing for my peers lol.

https://www.youtube.com/watch?v=TIfAkOBMf5A
- That's certainly something. Your song will also play at your funeral :)
  
  I see.
  I'll have to make arrangements so people know the red and blue dresscode is required too.

Devil Doll's 1989 "The Girl Who Was... Death" album, which is technically one very long track.