Complex sentence: It was also available on Windows 8 Pro and Windows 8.1 Pro as a paid add-on, before being discontinued in Windows 10, although it can be reinstalled unofficially through a command script installer.
Split into simpler sentences: It was also available on Windows 8 Pro and Windows 8.1 Pro as a paid add-on, before being discontinued in Windows 10. In Windows 10, it can be reinstalled unofficially through a windows command script installer.