Plesk enables you to set server-wide naming conventions for databases and database users, and also to configure the default remote access policy for MySQL database users.
To configure these settings, go to Tools & Settings > Database Hosting Preferences (under Applications & Databases). You can choose to add either the subscription's system user name or the subscription's external ID (an external ID can be assigned during the creation of a subscription via the API using the optional
external-id node) as a prefix for database names, and also to add the subscription's system user name as a prefix for database user names. This makes it convenient to find databases and database users belonging to a particular subscription. If you enable these settings, the prefixes will not be optional, and customers will be unable to remove them. However, the prefixes will only be applied to newly created databases and database users. Existing databases and database users will not be affected.
You can also configure the default remote access policy for MySQL database users (this setting does not affect PostgreSQL or Microsoft SQL database users). The chosen value will be used for all newly created MySQL users, but will not affect existing MySQL users. Note that customers whose subscriptions are granted the "Remote access for database users" permission will be able to change this setting on a per-user basis.