Control is absolutely free to try. When you sign up you get a Pro plan for free for one month, so you can try Pro features such as custom domains, unlimited publishing, unlimited projects and increased bandwidth and storage limits. 

After the free month, the Free plan keeps up to 3 projects, access to editor, and full list of components. Publishing and custom domains are not available on the Free plan.
To remove those limits, upgrade to Pro or Studio.
Every contribution genuinely helps us keep building, so if Control is useful to you, going Pro or Studio is a lovely way to support the project.