It shall be unlawful for any licensed retailer or his, her, or its agent or employee to suffer or permit any minor to be or remain in any room or compartment of such licensed premises where alcoholic liquor is being sold or consumed after 9 p.m. of any day; provided, that this section shall not apply to any minor who is accompanied by his or her parent or adult guardian, or to any licensed premises which derives its principal business from the sale of services or other commodities other than alcoholic liquor.