Limited membership

I have created a product called Helpdesk500! Those who purchase this product will be able to raise help tickets. I want to restrict count of the tickets to 10 completed tickets. When the buyer tries to raise the 11th ticket, His subscription should automatically expire and he should be prompted to buy the product again!

I am using a webform for the requests! I am struck how to make the subscription expire. Please advise

Posted: Oct 23, 2014