If it is needed to add some custom or specific information to a subscription profile, it is possible to do this by configuring editable fields within a subscription settings.
Such additional fields are called extended attributes. Extended attributes can be added to subscription using Parallels Business Automation API. For details refer to the Parallels Business Automation SDK.
Having been added, extended attribute(s) are grouped within a subscription properties, Account Director > Subscription Manager > Subscription, select subscription, switch to Ext.Attributes tab.