Your plan renews automatically the day before it expires, using the payment method you paid with. You are charged the plan's regular price, without any coupon or introductory discount. If a payment doesn't go through, we email you with a link to pay, so you won't lose any work on your site.
You can cancel your subscription at any time: go to My sites, open Settings for the site and click Cancel subscription. Nothing renews after that.
If you change your mind after a renewal, every plan has a 30-day money-back guarantee: ask for a full refund within 30 days of the payment.
An expired site goes offline. Renew within 30 days of the expiry date to get it back with all your data.