Our canine family members are predisposed to licking because it is one of their natural instincts. Licking is typically first experienced when pups are groomed by their mothers in their earliest days. It can therefore be associated with comfort and feeling soothed.
There are several other legitimate reasons for licking as well including: as a sensory tool (licking and tasting to dogs is like reaching out and touching to humans); to get attention; as a form of greeting; due to a behavioral disorder such as O-CD (Obsessive-Compulsive Disorder); or as a sign of affection.
If licking becomes too much of a preoccupation with your dog, you may need the assistance of a certified trained or a veterinary behaviorist.
If you have concerns, consult your dog’s vet first. Your vet may be able to help you get your pet to abandon this activity--especially during early stages of life as a puppy.