Here's an article on OCD type licking that will give you some of the basics of what it is and how it can get started. I don't know that I agree with that spray treatment or how it works - if it sprays in the dog's face or just emits the pheromones - but you can Google other articles about it also and get many ideas of how you want to best deal with it. A lot of dogs do this and particularly when in a competition with another dog for claiming you but of course many factors can be behind the reason for any OCD-type behavior.
Obsessive Compulsive Behavior in Dogs - Whole Dog Journal Article