You start with a great idea and now you have products out there in use by customers. You need a cradle to grave plan for PLM. What are your traceability requirements? How are your RMA's (both warranty and non) being handled? Do you need to make spares or FRUs and how do you track those to the product serial number? A lot of questions, and for each one a lot of defensible answers. The key is to adopt systems and processes that are right for your products and your customers.