Ala. Code § 45-49-91.23

A property owner or his or her heirs may continue to utilize a parcel of land in the manner in effect as of the effective date of the ordinance, provided, however, that if the property is reclassified for ad valorem tax purposes or if the property is sold to a person other than a family member, the ordinance shall then apply to the property and the property owner shall be required to comply with the ordinance or seek a variance under the procedures of this part.