Windows 8.1 is a service pack for the operating system Windows 8 and RT. First introduced and released as a public beta in June 2013, Windows 8.1 was released to manufacturing on August 27, 2013, and reached general availability on October 17, 2013, nearly a year after the retail release of its predecessor. Windows 8.1 is available free of charge for users of a retail copy of Windows 8 and Windows RT via the Windows Store. Unlike service packs for previous versions of Windows, Windows 8 users who obtained outside a retail copy or the installation of pre-loaded (ie, volume license) should get Windows 8.1 through the new installation media from each subscribed channel or company. Although not explicitly marketed as a service pack, Microsoft support lifecycle policy treats Windows 8.1 is similar to the previous Windows service packs: It is part of the life cycle support of Windows 8, and install Windows 8.1 needed to maintain access to the support and Windows Update after January 12 2016.
The Key Activation Windows 8.1 in October 2014:
New Retail Key Update Here