Cold weather can cause it

I understand that, but how, what actually happens, licking your lips does it as well, how?

Chapped lips, severa reasons for this. Moisture is within the skin. If you are not drinking enough non-diuretic liquids, then you are dehydrating. It's amazing how many millions of people are suffering maladies because they basically don't take in enough liquids. Ever had to pee into a bottle for 24 hours? I did, to test for heavy metals. I filled up a gallon jug in 24 hours. That's how I learned how much I need to drink (and that doesn't include sodas, beer, coffee which sucks your liquids from your body).

Lips get chapped when you sleep w/ your mouth open at night and when you have a cold. Your mouth is drying out too if you sleep w/ your mouth open (causes cavities too according to my dentist).

I lived in alaska...Just drank lots of fluids (wind dehydrates your skin) and kept lip protection on when I was outdoors in the winter.