N.J. Stat. Ann. § 45:9A-27

It is unlawful for an individual to engage in the practice of fitting and selling of hearing aids or to display a sign or in any other way to advertise or hold himself out as being so engaged without having at the time of so doing a valid unsuspended, unrevoked and unexpired license, temporary license or certificate of endorsement. Such license, temporary license or certificate of endorsement shall be conspicuously posted in the licensee's office or place of business at all times.