Ala. Code § 11-51-222

The governing body of any city which is subject to this division may, by the adoption of a resolution or an ordinance, exempt, from occupational license fees, in whole or in part, all persons employed upon certain designated parcels of land located within the city, for a period of not more than 15 years. The extent of the exemption and the period of the exemption shall be fixed in the resolution or ordinance.