A permissive Open Source license, also known as non-copyleft, is a free software license with minimal limitations on how you can use an Open Source code to create a paid-license program. You can use a permissive source code in your programs without crediting its software developer. However, you must attach an original copyright notice to your work to meet the license’s only condition. This leeway means you can use permissive-licensed software in proprietary software. A software team can protect products made with bits of Open Source under data rights regulations to restrict access. Apache 2.0 is the most popular permissive Open Source license. Notably, these licenses are more flexible than copyleft licenses.