Microsoft Support LifeCycle
Microsoft Support Lifecycle policy provides consistent and predictable guidelines for product support availability when a product releases and throughout that product’s life. By understanding the product support available, customers are better able to maximize the management of their IT investments and strategically plan for a successful IT future.
The information on this page is subject to the Microsoft Policy Disclaimer and Change Notice. Return to this site periodically to review any such changes.
Microsoft provides support on the current service pack, and in some cases the immediately preceding service pack, for the products listed below. See the Lifecycle Support Policy FAQ for details on the Service Pack Support Policy. If you have any questions regarding support for a product, please contact your Microsoft representative. If you need technical support, visit the Contact Microsoft Web site.
Source: Windows Phone 8.1 - Microsoft Support Lifecycle