If you just lost the key somewhere, I doubt a person finding it can match it to your Jeep. Of course, all they have to do is hit the panic button to find your Jeep, if you frequent the place you lost the key, and the finder has the patience and will to rip you off, you have something to worry about. Call your dealer and explain. Maybe they can change the code and basically render the lost key useless. I bet it will cost you a few bucks to reprogram your remaining key and car though, not to mention replacing the lost key. Sorry to be the bearer of bad news.