When you deploy "CloudGoat" you actually deploy some AWS services. You can be charged 1-3$ per day by AWS for using those AWS resources. However, thanks to Terraform you can destroy all resources just after finishing your play. You can also set up the AWS Free Tier account and AFAIK you shouldn't be charged anything for the first couple of hours. You can set up blilling alarms when you're close to reach Free Tier limits (more about it can be found here: https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/tracking-free-tier-usage.html)