High-end stuff usually has crap for UV filters in them. La Prairie is no different ( La Praire apparently has slept through all the UV filter updates in the last 15 years, tbh). Their lip pens are great for their nourishing properties and make lips look amazing, at least optically, but UV protection or useful antioxidants are non-existent.

Pharmacy brands offer best protection, if you are serious about protecting lips from darkening and premature aging. I prefer Bioderma's Stick Labial Solaire. Bioderma has two sticks, both are good, but this one is more transparent even applied in a thick layer, which is rare for a product with SPF 50+/PPD38 (once you try some lip stuff with effective UV filters you notice that they are either blue-ish or yellow, nasty, but then again, fully transparent stuff doesnt protect as well). Not high-end at all and really plain packaging, but it's the best there is, works under any conditions, beach, harsh winter etc.