Does it look like black, flat, asymmetrical lesion or it is red-blue-purple color?
Is this lesion blenching when pressed?

Its black, flat and I am sorry I dont understand 'blencing'

Sorry, I meant blanching not blenching (turning pale or losing the color when pressed on).
I guess when you press on that lesion the color stays same.
Lesion on lower lip that is with dark brown even color, flat and smaller that 1 cm in diameter, with well demarcated border, is very suggestive for melanotic macule.
This kind of lesion is harmless and its most frequent location is lower lip.
It is caused by increased melanin production, and, never turns in melanoma.
However, it is important to be biopsied to determine the diagnosis of melanotic macule, and, to exclude melanoma as diagnosis.

Best wishes!
Marija