MAK stands for “Multiple Activation Key”. MAK keys are used to activate a specific number of devices. The count is pre-configured as a deal between Microsoft and Enterprise. Every time a device is activated using MAK this is what happens: 1. When you try to activate your copy of Windows 10 via MAK, it will connect to Microsoft’s activation service, verify the key, and subtract 1 from the number of activation still available. 2. MAK keys are best suited for situations where machines are not reinstalled often. Because activation counts are not returned when you wipe a hard drive or reinstall your operating system.