In the case of any person making an initial application for a business or occupational license pursuant to Chapter 23, 25, 27, 29 or 43 of this title, the basic annual license fee for such initial year specified therein shall be reduced pro rata by the portion attributable to the number of full calendar months of the license year that have expired prior to the issuance of the license or, otherwise than in the event of any person making an initial application for a license, in the case of license fees under Chapter 23 of this title computed according to numbers of business units prior to such business units being placed in service.