My tip issues a van permit with 10 visits on it , easch time you attend they punch the permit , it does not have a expiry date . Mine is a 'resident' type permit for a non sign written/business van, I have seen sign written vans there and I believe they have a different permit. Mine is linked to the van registration AND type of van and my home address.
Ours is based solely on the vehicle type - basically the only thing that doesn't need a special permit for each visit (which you have to apply for 24 hrs in advance) is a car with no signwriting on it.