N.H. Rev. Stat. Ann. § 451-A:1

Any person who maintains an establishment for repair on radio or television equipment, who shall at his establishment or repair shop alter, repair or do any work on any such equipment at the request of the owner or legal possessor of such property shall have a lien upon and may retain the possession of any such article until the charges for such alteration, repairing or other work have been paid.