Existing, nonconforming billboards are exempt from the prohibition on billboards in section 5.72.010 of this chapter; provided, however, that any existing, nonconforming billboard located on premises owned by a third party lessor, licensor or the like shall be exempt from the prohibition on billboards in section 5.72.010 of this chapter only until expiration of the term for which such premises were leased or licensed for billboard purposes. In no event may the use of any existing, nonconforming billboard be expanded, increased or extended in any way, including, without limitation, by increasing the height or size of such billboard. Further, the term of any such lease or license shall not be extended beyond the original term unless one or more options to extend the original term are specified in a written agreement for the lease or license of such premises actually in existence as of the city's incorporation on November 30, 1999 and such option was formally exercised as required by such preexisting lease or license agreement prior to the city's incorporation on November 30, 1999. If any such option to extend the original term of any such preexisting lease or license agreement was so exercised prior to the city's incorporation on November 30, 1999, then the existing, nonconforming billboard in question shall be exempt from the prohibition on billboards in this chapter only until expiration of the term of such lease or license agreement, as so extended. (1999 Code)