Dogs normally lick to explore their environment and show affection, however the behavior can become a compulsion, with your dog licking furniture, you or himself constantly. When licking develops into a compulsive behavior, it is typically the result of boredom, anxiety or pain. If the licking is a result of pain, you will need to treat his discomfort before you can stop the licking, but if the licking is rooted in anxiety or boredom, a lifestyle change should be enough to stop the licking.
Provide toys, exercise and mental stimulation. Boredom is a main cause of dogs developing a licking habit. Keep your dog busy by providing alternative activities. Chew toys allow your dog to exercise his jaws and teeth, and relieve tension at the same time. Puzzle toys, where he has to work to free a treat from the toy, keep his mind occupied. Regular walks and obedience training work off excess energy and stimulate his mind.
Redirect his attention when he starts to lick. When you catch him licking, give him a firm "no" and toss a toy, ask him to come, or do something else that forces him to change what he is doing. If you simply say "no" and continue what you are doing, he will probably stop licking momentarily then go back to it, unsure of exactly what you want.
Teach him what you want. If he has a tendency to lick at specific times, teach him a different way of handling that time. For example, if he lays by you while you are watching television and licks the couch, tell him "no" and give him a chew toy. When he chews on the toy or lays quietly beside you, praise him with a "good boy" and a treat. If you consistently discourage licking and reward him when he is not licking, he will learn what you want.
Use a taste deterrent. Redirect dogs who like to lick specific things, like the arm of the couch or their own paws, by applying a commercial taste deterrent. Apply the product to the areas he likes to lick, following the package directions. While this will stop most lickers, a dog who is licking compulsively may simply find another spot to lick, so keep a close eye on him to prevent any new behaviors from developing.