Hey pedalpete, unfortunately we don't support legacy Windows Phone yet, but we do support Windows Phone 8+.
As for your question regarding a stolen phone, in addition to built-in device security (such as a PIN lock or remote wipe) we've provided a number of features that should help users in such a situation: First, the LaunchKey mobile app comes with two in-app knowledge factors (a numberless combo lock and a standard PIN lock) that can be enabled to prevent access to the LaunchKey app itself. Second, a user can enable geofencing or add a Bluetooth factor to prevent the device from authorizing outside specific geographical zones or when unconnected to specified Bluetooth devices (a FitBit, iBeacon, etc.).
While in theory an attacker could disable these services within the app, we've assigned 60 minute delays to creating or removing geo-fences and Bluetooth device factors. The idea being that you should realize your phone/device is gone within an hour, and within that time you can use our third protection: remotely unpair a device via the LaunchKey website or via another paired device, thus disabling that device.
Thanks for your feedback and please let us know if you have any other questions or comments!
(disclosure: I'm a co-founder of LaunchKey)