Ecommerce Plugin with Subscription Capabilities?

Is anyone familiar with a wordpress ecommerce plugin that functions as a normal shopping cart with digital delivery options but also has a subscription feature? The subscription feature would be so if someone purchased digitial download X that when product X version 2 comes out they get notified? And taking it a step further can purchase it for a discounted fee?

I am assuming what I am mentioning is not in existance & really should be custom programmed outside of using wordpress. But I figured I would check here since all my research has found nothing that would work.