NAT is ad free it relies on the generosity of donations via a link when the need for funds comes up.

More than likely it is some other program that is running. You have to be so careful downloading software anymore as many times boxes are pre checked to install other programs you may not want, like for extra browser bars and making certain things your default setting.

Can the OP post any screen shots so we can get an idea of what you see showing up on NAT.