Milestone XProtect Professional Camera License to connect a camera, one license per camera channel is required. In total, for all copies of the product installed under this license, the product may only be used with as many cameras as you have purchased camera licenses for. Video encoders and DVRs connected to multiple analog cameras require a camera license per channel to operate. I/O devices require a camera license per I/O device. An unlimited number of camera licenses may be purchased. To extend the installation with additional camera licenses, the SLC is required.