Infinite Touch license keys are sold online on Augumenta website at http://augumenta.com/hololens. We issue license keys on a per-application basis, which means that you need to purchase a license for each application separately.
A license key is locked down to your Product Name, which is found in Unity3D in the PlayerSettings dialog:
When purchasing the license, make sure the enter Product Name exactly as how it's saved in you Unity3D project; otherwise, the issued license file will not work with your application.
Please note that characters used in Product Name are currently limited to western letters, numbers, spaces, dots and dashes. We're looking into enabling full unicode character set in the near future.