Limiting windows accounts to five devices may have been one of the many bad windows 8 decisions but Microsoft made the call to back off from it. On a single windows account in Windows 8 and Windows 8.1 you will be limited to running windows stores apps to only 5 devices. You can buy an Metro app and install it on 5 devices at a time but you try to install it on a 6th device using that very account, windows store would only let you go ahead if you officially uninstall the app on one of the existing devices. Although not a big deal for customers yet a hard one for developers as it is hard for them to demo Metro apps with such restrictions. This limitation is experienced when it comes to all the Windows Store apps including the ones that are free. Thus Admin have to have at least two different Microsoft accounts if you they have six cloned Windows8/RT devices running Metro apps of any description.
Microsoft recently announced that now Metro apps can be now installed on up to 81 devices under the same Microsoft account effective Oct 9 and finally consolidating Windows Metro apps and Windows Phone apps in a single store, giving developers and customers more control. This also means more revenue from ad-based apps running on more devices.