Typically how long does geographic tongue last? i've had it constantly for months, does it ever go away?

It comes and goes: Geographic tongue is a totally benign condition of the tongue. It will change its appearance from time to time and may go away for awhile. You don't need any treatment for it.

Variable-no typical: Geographic tongue can persist for months or years. The problem may eventually resolve on its own but may appear again at a later time. It's usually a lifelong condition but is quite variable from individual to individual and varies even within the same individual over time in size, location, pattern and degree. Usually completely benign although may become sensitive to spicy foods.