What is the difference between monthly and annual billing?
The two available billing methods are different in regards to when the payment method is charged and in the total price.
The monthly billing plan charges your payment method on the first day of every month.
The annual billing plan charges once a year on the date when the plan was started, and offers a free month of subscription compared to the monthly plan.
The billing plan type can be changed in Settings -> Billing, clicking on 'Add more' in the Current plan section.