Is the the TurnItIn anti- plagiarism program worth the price?

I am a member of my school's PTA, and the school has opted to use the PBAT, a regents waiver. This PBAT exam is made up of essays on all subjects. The essays are graded by the teachers, parents, or administrators that the Principal chooses. I am concerned because of my principal's lack of integrety and honesty in choosing an honest and reliable grader. I am hoping that this program could help rule out essays that have been plagiarised so that cheating is not allowed and so the students could properly be evaluated.