You can easily update your credit card. Navigate to "My Account" page and click "update billing details" next to your listed membership. Take a look at the example below. The "update billing details" link is circled in red.
Recurring charge means your credit card will be automatically charged. Recurring charges occur for: Ayesha Membership - every 30 days; 15-day free access - on day 16th and every 30 days there after; Iron X Premium Membership - every year. You can cancel at any time, of course.
If you do not wish to be charged, please, cancel your membership before the billing date occurs. We do not refund for automatic payments or partial membership use. We do not refund if you cancel your membership after you got charged. We do not refund if you don't use the site.