Sitefinity Cloud uses Page views and API calls quota as two of the key differentiators between tiers.
Page views and API calls usage are assessed on an annual basis. This provides customers the option to cover their balance at the end of the current billing cycle. Customers can also pre-order pageview and API calls add-ons at favorable prices. Exceeding allocated quota does not result in service suspension.
Refer to the Sitefinity Cloud tiers page for up-to-date information on the current usage guidelines