Order with Plesk license fails:
Could not create License into Subscription #ID: Client authorization failed"
Connection to Plesk Key Administrator fails:
Home > System > Settings > Licenses > License Management Plug-in Name
Test Connection fails with an error message
"Vendor's Login/Password are not valid."
Verify if the username and password are correct. In case you are not aware of correct credentials or those you have do not work, please contact Plesk sales representatives (e.g. using the form or any direct Plesk sales team contacts).