The students do not have the finish PMA in one session. The next time they log into Stride, they will pick up where they left off. When a student finishes PMA, he or she resumes the normal questions provided by the Stride Adaptive Engine.
You may want to put the beginning dates for each PMA date on your calendar. Ideally, you should never worry about the ending date for a PMA. If your students are using the program, they will finish PMA far before the ending date.