Why do my stopped environments continue to incur usage charges?

When you stop an environment from running, your cloudlet utilization drops to zero, and you are no longer charged for CPU or RAM usage. These resources do not have to remain provisioned for you to re-enable the environment at a later time. 

IP addresses and storage, however, cannot be wiped clean or else you would lose your environment entirely. Since these are finite resources with an associated cost (whether you are actively using the environment or not), you will continue to accumulate usage charges even for environments that have been stopped.