The hippocampus along with the brain frontal cortex plays an important role in determining what individuals remember. Thus, the reason why one's brain will not allow them to forget a strong musical memory even at old age is because a song is accompanied by consistent words and beats making it easier for individuals to retrieve such memory. Besides, we constantly store memories in both our collective subconscious and unconscious hence a matter of retrieving them when we remember something.
The act of music triggering a certain event or memory is premised on the fact that music triggers both our implicit and explicit memories. Besides music is linked to movement hence activates numerous parts of the brain evoking strong emotions which play an important part in sealing our memories. This is through the stimulation of parts of the cerebellum and cerebrum that necessitate our motor abilities.