A great deal of writing is an act of commemoration. It's a grabbing on to feelings, thoughts, experiences before they slip away, and poetry is no exception.
For example, I haven't dialled my childhood telephone number for over a decade. I might be struggling to remember it by now if I hadn't written the following poem from Inventing Truth, my 2011 HappenStance pamphlet:
You worked your way round my milk teeth,
sung umpteen times before you stuck.
Soon a chameleonic code,
you were my safeguard from a snatch,
then my duty when staying out,
and recently a thankful leap
from trade fairs and dogged insects.
My fingers refuse to leave you.
Of course, my aim in this poem is to involve the reader, implicitly asking whether they too still recall their first telephone number. Well, do you?