We do not have any immediate plans to include eCommerce with our free version of the plugin. This largely has to do with the amount of support that will be needed when providing a feature like Ecommerce. Direct support is something that we cannot provide for free. More information on support we are able to provide for our free plugin, please check out this help guide: How do I contact you for support? / Where is the NextGEN Gallery support forum? 

We do have Ecommerce included in NextGEN Pro. Learn more about what is included in NextGEN Pro here, and review our support documentation for NextGEN Pro here.