Section 108M. A city or town which employs a permanent police officer who is enrolled as a student in good standing in a police, law enforcement, criminal justice or police career oriented course of study at a college or university accredited by the New England Association of Colleges and Secondary Schools, Inc., or the board of higher education, shall, subject to the approval of the appointing authority, and chief of police or any other officer having similar duties, pay said police officer his full weekly salary during the normal thirty-two weeks such college or university is in session; provided, that he is enrolled for at least sixteen hours of classroom instruction, works twenty-four hours a week on regular duty as a police officer in said city or town and during regularly scheduled school vacations works his regular tour of duty; and provided, further, that he is studying for a baccalaureate, master's or higher degree. Each officer who is enrolled in a college or university under the provisions of this section shall enter into an agreement providing that he shall remain in full-time employment as a police officer in such city or town after completion of such course of study for as many years as he has been aided under this section.