In CloudBees Build Acceleration Developer Edition version 7.1 and earlier, the agent software reads a license file that permits a certain number of agent instances. This message indicates a problem related to that license.
Check the details of the message for clues. The ecagent program may not be finding the license file. Or the license file may be expired, or inapplicable in some other way. Or it may specify a smaller number of agents than you wish.