Before creating a UserRoleBinding for a specific org_id, check whether the org's OrganizationProfile.license_user_limit has been reached. New users attempting to join a full org receive HTTP 403 with a descriptive message. Re-assigning a user already in the org (role change) is unaffected, as is assignment to an org with no OrganizationProfile. Co-Authored-By: Paperclip <noreply@paperclip.ing>