I consider it essential to have two keys. If you only have one, and lose it, you have no hope of getting into or moving the car. Then, a way will have to be found to reprogram everything to accept new keys. That'll cost more than getting second key now.
When on holiday, I always take the other key to either leave in the hotel, or give to my wife. In the old days, a magnetic box in the engine bay that I could reach from underneath.
A stitch in time etc..