73 Pa.C.S. § 7113
A township may not pass an ordinance imposing a license fee upon a manufacturer, including an agent, representative and employee, that is a resident of this Commonwealth for soliciting orders for or selling personal property manufactured within this Commonwealth if the township could not legally impose the same license fee upon a manufacturer, including an agent, representative and employee, that is a nonresident of the Commonwealth for soliciting orders for or selling personal property manufactured outside this Commonwealth.