org/wiki/Chapped_lips
Some causes of the symptoms you mention, could be
lip biting,
lip licking, Vit.B2 deficiency, smoking, overexposure to
sun and ill fitting dentures. In extreme cases, this could be due to bacterial or fungal skin infection.
You need to drink plenty of water daily – around 1.5 – 3 litres per day and eat a balanced diet. Do not keep your lips dry; apply lip balm which contains sunscreen – preferably a medicated one.