I have two. One in my wallet and one in the glove compartment. And even though one pass can cover others in the car you should get one for everyone who qualifies.
My wife had a lady come to her window in a park, alone in the car, and tried to use her husbands pass. When asked where the passholder was, she displayed the urn with his ashes. My wife had to explain that yes, this is a lifetime pass. When her husband expired, so did his pass. Rather than buy her own pass, she turned around and left.
Plan ahead folks, get the cheap pass. Spouses too.
Chuck Peck in CasaLoca