Microsoft Translator app on Windows 8, Windows Phone 7.1 and Windows Phone 8, will not be available in their respective stores as of March 22, 2017, and any installed versions will stop functioning on April 30, 2017.

Translator will still support Windows 8.1 and Windows Phone 8.1, with new versions releasing shortly. However, users will need to ensure their app is updated before April 30, 2017, to ensure it will continue to function.

There’s no change to Windows 10 PC Mobile.

Microsoft Translator Support for Windows Apps:

Windows 8 Windows 8.1 Windows Phone 7.1 Windows Phone 8 Windows Phone 8.1 Windows 10 (PC and mobile)
App removed from Store on
March 22nd,
App cease to function on April 30th
App update required by April 30th Y Y
No change needed Y

To update your Translator app for Windows:

Source: Microsoft Translator app end-of-life on older Windows platforms – Microsoft Translator Apps - Feedback and Support