In PBA-E Plesk license has Installation Failed status.
In POA Task Manager task
Plesk in VPS VPS_ID : install license (where VPS_IS is id of vps on subscription for which license installation failed) show the error(even if its status successful):
https://VPS_IP:8443/enterprise/control/agent.php : The requested URL returned error: 503
It means that port 8443 is not accessible on the VPS for incoming connections, as a result POA cannot install license to it.
Please make sure that Paralells Plesk Panel is running, also please chech if port 8443 is open on firewall.