They have gotten more strict about people not showing up for classes since last year. I guess they had a lot of no-shows. It says right on the enrollment site that they can void your tickets if you do not show up for your class. I know I had to click a lot of places saying I agreed to the terms and agreement.
The site says "Participation in scheduled Disney Youth Education Series Program is required to utilize the Disney Youth Education Series discounted packages. Disney Youth Group Programs reserves the right to void ticket packages without notice if the student does not attend the scheduled Disney Youth Education Series Program".
I don't know what they would do if you signed up for a class that happened after you had used all your ticket days. I would feel bad for taking a spot that another family might have actually wanted though. I would also fear that they would black list me and I wouldn't be able to use the program in later years. My son got sick the day before his class last year and was laid out for 2 days in our condo. I called and let the YES people know he wouldn't be there and I kept the check out slip from the dr. in case I needed it to use the program this year.
I actually think if you are a no-show and don't have a documented excuse, they should be able to charge your card for the difference. It's breaking the rules, just like telling them your 3 year old is still 2. If a lot of people do this, they will get rid of the program altogether. Just my opinion of course.