The cost is 7500 pesos for a license. The license is a piece of paper with several rules that you must follow. I have not seen the paper, but from what I understand is that there is no more night driving, no rentals, no putas as passengers. Maybe somebody who has bought one can chime in and post the rules. AMET is in charge of enforcing.
All in all, this is great news for everybody. 7500 pesos is cheap and finally the city woke up and decided that they can make money by allowing the carts back on the road.
Same as with the LED lights. I bought a license and I'm back blasting idiots who drive with their bright lights on every morning.