How many lenses can I calibrate?
Reikan FoCal does not limit the amount of lenses you can calibrate with a registered camera.
Internally to the camera there is limited memory to store lens calibration settings. This limit on certain older cameras can be as low as 12, most cameras allow around 20 lenses (some of the most recent cameras allow up to 99 lenses!).
Specification does vary and can be checked in the camera's user manual if an exact figure is needed. Most users find the camera limit is much greater than the number of lenses they might use.