Control periods for restricted ownership units shall be in accordance with N.J.A.C. 5:80-26.5, as may be amended and supplemented, and each restricted ownership unit shall remain subject to the requirements of this section until the Borough of Englewood Cliffs elects to release the unit from such requirements however, and prior to such an election, a restricted ownership unit must remain subject to the requirements of N.J.A.C. 5:80-26.1, as may be amended and supplemented, for at least 30 years.