Iso2mesh is an <strong>open-source software<strong>. That means not only you can use it for free, but also you can read the full source code and learn how it works. If you want, you can modify iso2mesh's source code and make it better. Your modified code are allowed (legally) to share with other friends and colleagues under the same open-source terms.
An open-source software depends on contributors to get better and better. A contributor can be a user, or a developer.