I checked their site and in the FAQ section, they say that most versions are good for three years, some for two. And they don't say which is which.

I called the maker, Pfizer, and the lady said that three years is as much as they know about, not having tested it for longer periods. She was shocked when I mentioned how long some here have used it!

I suspect that it lubricates the lips okay longer than it protects against sun. They do list SPF (?) ratings for the sunblocker effect of different flavors and versions. This is only about trademarked Chapstick products, not for other lip balms.

I did open the package that I found, and it seems normal. But it is probably within their three year limit. I'll get another tube tonight and mark the pkg. as to purchase date, but there's no way to know when it was actually made. The Pfizer lady said that she'd pass on my request to mark expiration dates.