The first step is to create a USB Recovery Drive, windows.microsoft.com/.../create-usb-recovery-drive.
Hello, I have bought "Vostro 3900 Mini Tower (Late 2013)" that came with Windows 8.1 preinstalled. For System backup, upgrade to Premium account is needed. Once I pay for Premium - Is this charged one time or automatically renewed periodically? Thanks! 
How to reinstall windows 8.1 if it crashes