Mark the lesson where the package was purchased as "Delivered" and select a "Block purchase" as the payment amount. Alternatively, from a pupils profile tap "Record a payment" and select the lesson in question that way. Their profile will be updated to show the amount of package time they have remaining. See our How to Record a Lesson Pamyent guide if you would like a detailed breakdown.
You can then go through each of the other past lesson, marking them as "Delivered", then select "Deduct from lesson package" to reduce their package time until your lessons are up to date.