They need to use the spare key, I.m having the smartphone option done tomorrow, and they didn't say if they need the spare or not, since if the spare is in the car anyone can use it.
Do NOT need a spare care with the Viper option. Car starts, and when you enter the car you have to press the break. If you do not have the key with you when you press the break, the car shuts off. If the key is in your pocket, the car keeps running and off you go!