Key Fob Issue/Tire Pressure Light

Bidness91

hello all. I just picked up my 11' 370z last friday and I have a couple issues that Im trying to figure out.First of all, I bought it from an infinity dealership so they didnt give me the runaround of the car or the various features (like you would get if you bought it from a nissan dealership). I also did not get a second key from them, but they are in the process of finding the previous owner and sending me one.

anyways, I drove the car home with the key in my lap and several other times with it in the cup holder. another drive the next day it said there was no key present so I put it in the key holder slot to start the car. now, everytime i try and start the car it is making me put it in the slot or it says 'no key'. did I turn on a setting or something? how do I turn it off?

also, I was getting a tire pressure light, so I filled them all up and the light is still on. how do I reset it? could it just be a bad sensor? thanks.