The Beta List plan is a Free plan that also has access to additional features typically not included in the free plan, such as publishing your Collections and Blogs. 

If you downloaded AMP prior to August, 2018, you were automatically enrolled in our "Beta List" plan on AMP 1.0.  This plan, as mentioned in AMP 1.0, gives "Access to all features released on or before August 2018". 

Does the Beta List plan work with AMP 2.0?

For the most part, no.  If you want to publish pages using AMP 2.0, or take advantage of additional features like Custom CSS, and our improved rendering engine, as well as dozens of other enhancements, you will need to upgrade in order to use these features.  If you aren't keen on upgrading, you can keep using AMP 1.0 forever. 

To gain access to these additional features on AMP 2.0, you will have to upgrade your account by heading to your account page and clicking "Change plan".  If you aren't ready to upgrade, you can still take advantage of your Beta List plan forever, and you can swap freely between AMP 1.0 and AMP 2.0 at will.