License4J is a pure Java library for creating and validating licenses. The key concept is features of a license. You can easily add any feature to your license file, i.e. name of the product, version, expiry date, number of executable instances, customer's name, company, and IP address. The feature's value can be string or any serializable Java object.
Full Specifications
What's new in version 1.6
Version 1.6 generates and validates string serial keys and is stronger obfuscated by Allatori Java Obfuscator v3.1.