Dogs like for several reasons.
The first reason is simply to taste something. If it’s tasty, your dog will keep licking. Like when your dog comes across some peanut butter somewhere, he will keep licking and licking until it’s all gone.
The second reason is to keep clean. Your dog usually licks himself after going potty. Dogs will also something engage in social grooming when one dog licks the fur of another dog.
Also, sometimes dogs will lick wounds to help them heal. Dogs also lick wounds of others to help them heal.
To Show Affection
Third, and this is the reason that is most likely when your dog is licking you: to show affection. Put simply, your dog likes you.