The license defines how many mining processes (e.g. Cgminer, Claymore Miner) that can be prepared and monitored.
For ASIC miners like Antminers, one miner will consume one license.
GPU mining: In most cases one license is consumed per mining computer, as long as only one instance of the mining software (e.g. Ccminer, Claymore Miner) is running. In scenarios where a single mining computer is running multiple mining software, for example Claymore Miner is running on 3 GPU's and Ccminer is running on another 3 GPU's, there will be a total of two licenses consumed. If CPU mining is running on the same computer, an additional license for the CPU mining software will be consumed as well.