Imunify360 extension cannot be activated with a license purchased from Plesk.
The following error is shown when accessing Imunify360 extension:
Servers limit exceeded for key <KeyNumber>
Imunify360 license can be used on one installation at a time.
The error may appear due to one of the following reasons:
More than one Imunify360 is are activated with Imunify360 license.
Imunify360 has been reinstalled on the same Plesk server, thus the same server to be registered twice.
If the old server where Imunify360 is activated with the mentioned <KeyNumber> is still online, run the following command to unregister Imunify360:
# imunify360-agent unregister
If the old server is offline, contact CloudLinux Support for further assistance.