N.H. Rev. Stat. Ann. § 276-A:18

Laundries may be granted a special license by the commissioner excepting them from RSA 276-A:11 and 12 for not over 3 months of the year, but in no case shall the hours of labor exceed 60 hours in any one week, nor more than 10-1/4 hours during any one day. Before granting such license, a hearing shall be held by the commissioner and he shall be satisfied that such overtime is necessary. A copy of such license shall be posted where youths are employed. This section shall not be applied in any way to the disadvantage of any regular employee.