The 12 month option was only recently introduced. Previously it was only 6 months. And now you have the option of either 6 or 12 months.

And yes, after the end of that period, your name will be automatically removed from their database. Over the last 30 days of your support period, it will show on your personal pro download page that your support is nearing an end & they offer a discount to continue. That's why I always recommend pro users to bookmark their download page so they can check it periodically.