Cloud Monitoring is billed monthly, based on three factors:
With each check you create, you can monitor a specific resource, at any frequency, from up to 5 monitoring zones. The frequency of a check doesn't affect the price—so you can run your check as often as you need, without additional cost.
If you add a Managed Cloud Service Level to your account, you get up to 8 checks from 3 zones, free of charge. Learn more about the benefits of a Managed Cloud Service Level.