Depending on the brand and model, losing the last working remote for a vehicle could be very expensive.

IIRC some factory security systems cannot be over ridden, even by the dealer, if there is no usable remote with which to program another (factory new) remote.

I always have (at least) two working remotes for every vehicle. Not only could a remote fob be misplaced/lost but it is also possible for one to be unexpectedly damaged (stepped on, water damage, whatever). And I maintain good batteries in every remote, and will from time to time verify that the ‘other’ remote also still works the car.