I do not keep the targets but do keep the performance checklist which has a spot I date and sign as the instructor, that states I witnessed the student safely shoot at a target on the range. The student also reviews and signs this checklist. This is kept along with the graded test and registration info for the student.
Florida statutes 790.06 states this
7. Completion of any firearms training or safety course or class conducted by a state-certified or National Rifle Association certified firearms instructor;
A photocopy of a certificate of completion of any of the courses or classes; or an affidavit from the instructor, school, club, organization, or group that conducted or taught said course or class attesting to the completion of the course or class by the applicant; or a copy of any document which shows completion of the course or class or evidences participation in firearms competition shall constitute evidence of qualification under this paragraph; any person who conducts a course pursuant to subparagraph 2., subparagraph 3., or subparagraph 7., or who, as an instructor, attests to the completion of such courses, must maintain records certifying that he or she observed the student safely handle and discharge the firearm;