Although many humans interpret their dog licking their nose and mouth as “kisses” and a show of love and affection, this is likely a stretch. Licking is a habit instilled in your dog from the very beginning of his life when, immediately following birth, his mother licked him clean.
One explanation for the licking is that your dog is soliciting food. Some wild dog pups, including wolves, who are still too young to eat directly from an animal, lick their mother’s face to signal to her that she can regurgitate food for them to eat.
The more common explanation is that licking is usually a show of submission and obedience. In a pack setting, for example, the less dominant dogs lick the alpha dog to demonstrate their submission.