a. In addition to any other tax or fee imposed by this act, there is also hereby imposed an annual license fee of $500.00 upon every slot machine; maintained for use or in use in any licensed casino establishment in this State.
b. License fees imposed under the provisions of this section shall be imposed as of the first day of July of each year with regard to all slot machines maintained for use or in use on that date, and on a pro rata basis thereafter during the year with regard to all slot machines maintained for use or placed in use after July 1.