Per the BBS an MFT intern may renew his/her registration no more than five times. Note that an intern may only work in a private practice setting during the period of the first intern registration.
“The registration may be renewed a maximum of five times. No registration shall be renewed or reinstated beyond six years from the last day of the month during which it was issued, regardless of whether it has been revoked. When no further renewals are possible, an applicant may apply for and obtain a new intern registration if the applicant meets the educational requirements for registration in effect at the time of the application for a new intern registration. An applicant who is issued a subsequent intern registration pursuant to this subdivision may be employed or volunteer in any allowable work setting except private practice.” [Cal. Bus. & Prof. Code Section 4984.01.]