Ask HN: How can I monetize my product without charging for it?

So, here is my issue. I am writing a suite of development tools for C / C++. As I get closer and closer to completion, I am facing this issue. I want to make them freely available to the public, I don't believe in charging people for software, especially since I love doing it so much. I also don't want to open source my work, for security reasons. I was thinking I could make it free for everyone, and businesses who want support can pay an annual fee?