If you use an expiration date, you must have stability data to prove it is good at least past that date. You must do it before you start using the date. You must have stress testing and then real time data utilizing a stability chamber with controlled temperature and humidity. You must keep records that will stand up in court, because to have printed a guarantee that the product will remain good.
Many (but not all) companies have a pull by date agreement with their customers.
I think most soft drinks have about a six month shelf life. I am almost certain that is the date if artificial sweeteners are used as they tend to go bitter or off taste after that long.
Product stability is a big deal and lots of companies avoid it if they can.
This post was edited on 5/30 at 12:25 pm