In Agile, you are supposed to ship product on a regular cadence. All features are added to a product backlog, divided into small projects that fit within a sprint, and then prioritized. The backlog is just a way to keep track of all of the ideas people have, requests from customers, major bugs and other things.
The first patent for Pristiq is set to expire in February 2022. This is the earliest predictable date that a generic version of the drug could become available. However, other circumstances could come up to extend or shorten the exclusivity period.
Nothing happens to a provisional patent application one year after filing. After the one-year point, that provisional application for patent can no longer be used as a priority-date for a non-provisional application. The provisional application is not examined by the examiner or used for any purpose regarding any non-provisional application that may be filed after the one-year term expires.