The Siemens part number 6AV6381-2BL07-5AX0 refers to SIMATIC WinCC system software V7.5 SP2, RT 262144. 

Runtime software supporting up to 262,144 PowerTags

Single license model

Delivered as a set of 3 DVDs plus a USB flash drive containing the license key

Supports 5 languages: German, English, French, Spanish, and Italian

Compatible with:

Windows 8.1 Standard/Professional/Enterprise/Ultimate (64-bit)

Windows Server 2008 R2 SP1 (64-bit)

Windows Server 2012 (64-bit)

Classified as a Class A product (standard stock item)