Microsoft Windows 8.1 Pro Pack (Win 8.1 to Win 8.1 Pro Upgrade) - Key Card Upgrade your Windows 8.1 device to Windows 8.1 Pro with Pro Pack Box Included 1 upgrade license code used to download the upgrage Connecting to company networks with Domain Join, and Windows Media Center Remote Desktop access from one PC to another and encrypt your data with Bitlocker Windows 8.1 Pro pack will not work if your current OS is older than Windows 8.1. You must be running Windows 8.1 "Core" to use the Windows 8.1 Pro Pack upgrade.