Sir 15k is quite reasonable for it. In Lahore it costs around 20-25k for corolla.
It will be automatically removed with time, This is what i know. The coating gets thinner with time and in the end you are only left with your genuine clear coat.
In all things bro. You will be having a protector like coating on your car. Its like you get a new phone and install protector on its screen, same is the case with glass coating. It will prevent against scratches, swirls and oxidation. In proper glass coating procedure they also protect your upholstery, trims, interior, glasses and all. It also prevents your car from dirt and provides extreme water beading for years.