Well, it seems you put it in a 'safe place'. You're lucky you found it! I've put many things in a 'safe place' that was so safe, even I can't find them.
My Dad once put my car keys in a 'safe place' because he thought my brother would take my car. That night, when I was ready to go to work, my Dad (who'd had a stroke several months before) couldn't remember where the keys were. I called in sick to work and got the spare keys from my Mom when she got home from work.
About 5 years later, after my father died, my Mom moved from the house. During the course of cleaning the house out, the keys turned up. They were buried in dirt in a planter my Mom had in the house! We all had a good laugh when we found them.
The car was in car heaven for several years by that time...