I was able to sign up for Premium Lite, basically downgrading from regular Premium. They do hide it a bit. On the Manage subscriptions page, it only showed the 3 normal ones (standard, student, family.) But when you go to the next step after picking one, there was a second screen. The upper part still had those 3, but if you scrolled down, there was a section that said something like if you only want fewer ads. That is where the Premium Lite was hiding.