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.
US patents with a filing date before June 8, 1995 provide protection for up to seventeen years counting from the date of grant (the date given with reference numeral 45), or 20 years from the filing date, whichever expires later. However, the patent holder is required to pay maintenance fees to keep his patent valid. In most European countries, these fees are yearly. The USA requires maintenance fees to be paid at 3.5 years, 7.5 years, and 11.5 years after issuance. If the holder does not pay a maintenance fee, the patent becomes abandoned.