Thanks, we will consider this, and in the meantime will improve the appearance of the tabs on mobile devices.
We’re planning to build this into the next version of our new Content Drip extension – http://www.woothemes.com/products/sensei-content-drip/
One alternative way to do this would be using Groups as described in this post – http://www.woothemes.com/2014/02/creating-a-tiered-membership-site-with-sensei-and-groups/
When you create a product that grants access to a Group, it allows you to set a duration, after which the user will be removed from that group.Sol Huebner commented
Is this one "fixed" with the release of the dripped content addon?