Dogs use physical contact in many ways when interacting with people, and licking is common. Research shows that dogs have a strong social orientation towards people, but it does not support the idea that every lick automatically means the same thing. A dog may be seeking contact, responding to attention it has previously received after licking, or simply investigating the smell and taste of the skin.
So look at the context. Does the licking happen when you come home, when your dog wants contact or when it is wound up? A behaviour that gets a positive response from people can easily be reinforced over time. If you do not want to be licked, calmly redirecting your dog to another behaviour usually makes more sense than trying to interpret every lick as an emotional state.
Licking you is rarely a medical problem in itself. If the behaviour suddenly becomes intense or compulsive, and your dog also shows anxiety, changed behaviour or starts licking its own body a lot, it may be worth discussing with a vet or a behaviour professional.