N.J. Stat. § 45:9-14
Any applicant who shall have been examined and licensed in accordance with the provisions of this chapter, who, when admitted to the licensing examination or when granted a license without examination, was a citizen of a foreign country and had declared his intention of becoming a citizen of the United States and who shall have been issued a license or shall have become entitled to a license valid for six years from the date of such declaration of intention and who shall fail to furnish to the State Board of Medical Examiners prior to the expiration of said six years evidence of his having actually become a citizen, shall have a further period of two years from the date of expiration of said six-year period within which to furnish to the State Board of Medical Examiners evidence of his having actually become a citizen. If the applicant fails to furnish to the State Board of Medical Examiners evidence of his having actually become a citizen within said extended two-year period, he shall be required to surrender his said license, which said license shall for such reason become invalid and automatically revoked and his registration shall be annulled; provided, however, that should the license of any applicant expire before the passage of this act, such license shall be reinstated immediately after the effective date of this act and such applicant shall also have a further period of two years from the date of such expiration within which to comply with the provisions of this section.
N.J.S. § 45:9-14