A few months ago, Gartner published this report: Cut Software Spending Safely with SAM

Organizations can cut spending for software licenses by as much as 30% by implementing the three software license optimization best practices presented in this Gartner research report, including:

Optimizing software configurations to achieve compelling savings by leveraging entitlements.
Recycling software licenses by optimizing your daily IT operational activities.
Leveraging software asset management (SAM) tools to scale your software license optimizations.

The Gartner report provides several vendor specific examples, using IBM, Microsoft, Oracle and SAP, to illustrate how you can cut software spending.

IBM—Optimize Processor Value Unit (PVU) licenses for full capacity and sub-capacity (virtualization capacity) licensing. (See also this blog: An Alternative Solution for Managing IBM Sub-capacity Licensing).

Microsoft—Optimize by understanding Client Access Licenses (CALs), optimize profiles for different subscription plan levels—e.g. for Microsoft Office 635, leverage Product Terms (aka Product Use Rights), and more.

Oracle—Optimize by choosing the right edition and license metric, select the right virtualization approach, etc.

SAP—Optimize SAP Named User Licenses by tracking and analyzing usage to select the optimal user type, find and eliminate idle and duplicate users, etc. (Read the whitepaper: Curing the SAP Overpayment Syndrome)

For a limited time, you can freely download the Gartner report from the Flexera Software website.