When a project is created the number of hosts available for the project is specified in the Project Settings. In addition each project is configured for the number of allowed concurrent runs and Vusers. These values may be adjusted using "Lab Management->Project Settings".
If a test is created, in the Performance Test Designer, where the number of hosts exceeds that specified for the project, after the test is saved, a validation error (in the "General Details") is reported with the following format:
The number of requested hosts (<n>) exceeds the project limit (<n>)
for example:
The number of requested hosts (1) exceeds the project limit (0)