Unable to use Plesk when there are more domains created than allowed by the license. So if the number of domains exceeds license limits, Plesk stops working. Plesk shows license error when trying to login or right after new domain has been created:
Error: The license key is invalid. In order to use Plesk, please obtain and install a new valid license key.
The amount of currently used resources overrides the limits defined by your license.
The number of websites hosted on the server exceeds the limits defined by your license. You have 11 sites hosted; your license allows hosting only 10 sites.
This is an internal issue with ID #PPPM-2595 , which is planned to be fixed in future product updates.
Delete redundant domain by the command below:
/usr/local/psa/bin/domain --remove <domain_name>