Another reason a dog licks is because he has been unintentionally trained to do so. He has learned that he can get almost anything he wants - especially attention from you. Even though you may have tried to discourage him, he's been interpreting your actions as even more fun and attention. Sometimes, it just develops into a habit. Your dog licks because he likes it, and he thinks you like it too. It is perfectly normal for dogs to express affection in this manner.
Don't forget the possibility that the dog just likes the taste of your face cream or body lotion or body salts.
Some dogs get carried away with licking when they are in their owner's lap because they are so excited and happy to be there. In such cases, it is best to spend a weekend or several evenings holding the dog on your lap in order to reduce the novelty and excitement of the experience. The dog should be picked up and held until he settles down to doze. During this session, verbal communication should be soft and gentle so the dog doesn't become overly excited. This procedure should be repeated over and over until the dog learns that getting on your lap is not a special event.
If he begins to lick you again, squeal or yelp as if in pain. Your dog will learn to stop licking because he does not wish to hurt you. Applying lemon or hot sauce to your skin will make it taste unpleasant to him and this will also help break him of the habit. (It may not however be good for your skin, so be sure to rinse it off as soon as possible.) If your dog is sometimes rewarded for licking and at other times reprimanded for it, he will almost certainly be confused. So teach your dog to 'kiss' on request and 'no kiss' on request. Only let him lick you if you say it's okay to do so. If you don't want to be licked, then politely request your dog to 'no kiss.' If your dog has been indulging in this behavior for a long time, then it will also take some time for him to learn to stop, so be patient. After all, he is only licking you, not biting you.
If you decide to stop your dog's licking behavior, then be sure that he has another way of expressing his affection. Some dogs like to jump up on the owner in greeting, other like to shake hands or roll over for a tummy rub. Training your dog to do a trick such as 'sit up, shake hands, roll over,' will give him a less sloppy way to ask for attention. When he forgets himself and tries to lick you, you can rechannel his behavior.