This leads me to the general question: Howto handle Customers already purchased assets or contracts. Maybe I go the route to integrate an existing CRM System based on Drupal with zencart. (Single Login or not) But I also want that
the customers are in full control of what they already have (Customer self service).
Also the possibility to create an order for the customer from the admin side would be nice. Like correcting or filling his shopping cart, and then sending him an email with the link to the order. (Maybe this way the recurring subcriptions could be handled, with some help from the shop administrator)