Do i need the license for xpack features such as machine learning?

on this page:

It has been said that You have opened the code of X-Pack features such as machine learning, But on this page:
you say that use of machine learning features requires licensing.

Now, is using the xpack features (Especially machine learning) free?

Open does not mean free. As the article mentions;

All free features are included and enabled by default and will never ‘expire’, and commercial features are opt-in via a trial license. The license for free features never expires,you no longer need to register to use these capabilities.