Microsoft previously disabled side loading of Metro apps. This happened in the Windows 8 era. You either had to purchase a side-loading key (per machine) or use

Microsoft previously disabled side loading of Metro apps. This happened in the Windows 8 era. You either had to purchase a side-loading key (per machine) or use Windows Enterprise. My memory of the details is fading, thankfully, but I think side loading was disabled for 8.0 and 8.1 (without a key), and the restrictions were removed or relaxed in 8.2.