Used to keep it in drawer at home until recently when I took my car for MOT and the mechanics couldn't get my car started to get it into the workshop. The dashboard said "key not detected"
I tried, they tried, no good. Rang the main dealer who's solution was to send a low loader to take it back to their workshop at huge cost!
Then one if the mechanics said it could be the battery in the key, which I hadn't changed in ten years! We didn't think that was the problem though as the key had opened the car.
In the end I phoned my daughter, asked her to drive to my house, get in with her spare key and bring my other car key, which she did.
Problem solved.
Next day I went to main dealer and had the battery replaced in the dead key and now keep it in my handbag. Thinking about it though, I should just keep a spare battery in my bag and leave the key at home just in case I ever get my bag stolen.