This is natural melanin pigmentation. If you have a short upper lip this is seen.
Depigmentation treatment is the simple procedure where in we can remove the upper layer and new layer will form. You can also try crown lengthening as a part of smile design protocol.
Next Steps
Consult a dentist if you wish to change your look
Health Tips
This is a natural variation unless you are a heavy smoker you can take it easy or else go in for cosmetic treatment as suggested earlier