The Procedure.subject is required to be a Patient | Group.  The Procedure.reason is defined as "The coded reason or reference why the procedure was performed. This may be a coded entity of some type, or may simply be present as text, or may be a reference to one of several resources that justify the procedure." Procedures are performed for more specific reasons than just because a practitioner / organization holds a given license. The license is a credential concern, not a reason to perform a procedure on a patient or group.