Why "Machine Quota Exceeded" message and How to resolve it.

The message "Machine Quota Exceeded" occurs when

KSE: The number of machine IDs is higher than the number of licenses

KRE: The number of sessions is higher than the number of licenses.

Solution:
Remove all machine IDs in the Registered Machines block under the Katalon Studio Enterprise or Katalon Runtime Engine tabs from the Admin Page, and try to execute tests or activate Katalon Studio again.