So you can enjoy continued access, without having to re-subscribe every month. If you don't like this idea, you can cancel it in your account profile.
An example of recurring subscription is:
You join on March 17th, for $16.95, for 30 days access.
On April 17th, you are charged another $16.95.
On May 17th, another $16.95, and so on.
Recurring payment are only for 3 days trial, 30 days and 90 days.
After you purchase a 3 day trial account, you will be automatically billed for 30-day subscription after the 3 days expire.
Premium Memberships for 365 days is one-time payments.
At any stage, you can cancel your recurring subscription. You'll have access up until the next rebill date, but you won't be rebilled - your account will become free on after last day of premium.