Having lost a key in the past that cost a fortune, I now subscribe to a policy called Keyfob. Costs £4 a month and they provide a fob you attach to the keys so you can track it and ping it if you misplace them. They also offer £100 reward to anyone who locates your keys. If you lose the keys, they recover you and your car and pay for your new key and any work needed done to your car locks.
nice to have the security and peace of mind.