I like the idea and the company seems legitimately concerned about protecting privacy (yes I read the entire EULA). Their servers wouldn't respond when trying to link my site with their app, however, so the process failed. That's a critical element you need to be aware of when using a setup like this: you are inviting increased complexity and dependencies. The client device, the cell or wifi coverage for the device, the LaunchKey servers, etc. If a customer chooses to use this approach on my website and runs into problems (even due to their own making), it reflects poorly on my company. The complexity may be beyond the average user out there. For in-house or personal use it may be fine, but I would be cautious about using it for the public. I would certainly keep it only as a voluntary option.