Yes, most accounts are automatically set up to renew automatically.
Bitcoin Cash, iTunes, any gift card payment methods through PayGarden, and region-specific options through Paymentwall, Bitcoin, Ethereum, Litecoin, Bitcoin Cash, or Bitpay do not automatically renew.
This is outlined in the Fees section of our Terms of Service, which you agree to upon signing up.
You can cancel the account at any time to prevent auto-renewal. Your account will remain active for the remainder of the time that you have already paid for, then will be canceled at the end of the paid time. Once canceled, an account cannot be reactivated, and you will have to sign up for a new account in order to use the service.