Microsoft Software Inventory Analyzer 5.1

Perform scans and inventories of the Microsoft software installed on a single PC, as well as access the inventory data of multiple machines via the network connection. The program creates reports with detailed descriptions, including the license numbers, of all Microsoft products.

Whether you have just a few computers or a large network, a software inventory tool can make it easier to quickly know what you have and how it's being used.
The Microsoft Software Inventory Analyzer (MSIA) is a free tool available for download that can help you with your software inventory. It is built specifically to be a starting point to working with SAM.

You can use the MSIA to scan and inventory the Microsoft software that is installed on a single computer, or on multiple computers throughout a network. It generates a report that provides details of all installed Microsoft products, including the type and the number of licenses. The MSIA will work with networks that have 250 or fewer computers.
As benefits :
Free for all customers
Easily produces html and excel based reports
Allows MLS report consolidation
Agentless tool
Report for up to 250 pc’s or devices at a time
Combine multiple reports for networks with more than 250 PCs
Localized in 31 languages.