Keygen - A dead-simple software licensing API built for developers
Labs64 NetLicensing - Monetize your digital products and services
CodeMeter - License Management
VMProtect - VMProtect Ultimate - All-In-One Solution For Software Licensing And Protection.
LockBytes - LockBytes is a Lightweight DRM (Digital Rights Management) solution for licencing Windows executable files.
SoftwareKey Licensing System - SoftwareKey System is a set of software development tools that help programmers implement copy protection, license activation and management, metering, eCommerce, and business automation.