Booked lessons are available to schedule for up to 6 months after the purchase date. The lesson can be scheduled for a date past the lesson's expiration date.
For example, you purchase five private lessons on July 4, 2016. You must schedule your five lessons before January 4, 2017. You can take any of those lessons after January 4, 2017, so long as they were scheduled before January 4, 2017.
Find the "schedule by" date of your lesson listed in your unscheduled lesson page.