In addition to being employed in the sale of beer and wine in accordance with § 4–504(b) of this article, an individual at least 18 years old and under the age of 21 years may be employed in the sale of liquor. A license holder may not make an off–site retail delivery of alcoholic beverages unless: the deliverer is at least 18 years old; and the individual taking possession of the delivery provides the deliverer with written certification that is: in the form described under § 4–506 of this article; and supported by documentary proof that the individual is of legal age to purchase alcoholic beverages. Each certification executed under this section shall be retained by the license holder for at least 1 year. A certification shall be available for examination during regular business hours by an authorized representative of the Board. The Board shall adopt regulations to carry out this section.