Lip colour shouldn’t be a cause of worry as lip/skin colour is attributed to genetics. However, it may occur to some because of habits like lip biting, lip licking, lip peeling.and if its cause my drinking excess tea or coffee then cut down your drinking habits...you can visit your doctor to rule out any medical causes..
You may try application of lemon juice daily. Visit a cosmetic-clinic for new age solutions like “permanent lipstick” to have a natural pinkish colour of your lips. This technique is very safe and without any side effects.