This isn't just any key

Right. I have started to pack my clothes, shoes, shoes and ummm shoes in my suitcase to go back to Uni and I came across this small key. This key has been the bane of my life at uni for about 6 months because it went missing and it opened our flats postbox. We'd have to cough up £ if we wanted another one and of course being stubborn students as well as tight we decided to force our hands through the flap of the post box to retrieve our mail which mainly consisted of junk leaflets. Everyone was adamant one of the random boys we had to share a flat with had misplaced it. I even accused him of being careless and to stop nagging us and blaming us for losing the post box key of 12.2.9.
You can see where I am going with this story. 6 months later here I am with it on my bed next to me. All my flatmates found it hilarious after I sheepishly told them what I had found. I informed them I was bringing it to the new house this year as a good luck charm... Hopefully this will be the only thing to go missing throughout uni life and nothing more valuable.
Roll on year 3!