It's difficult to make money from open source.

You fix this mistake by closing the source, ie taking any source code offline and continuing to develop it with closed source.

To make money, you sell the software for a fair price.

Payment for access to expanded and more powerful feature sets offered under a different license model is very common.

Similarly you can contract to build specific features, possibly under a different license open or closed.

If you do any contract work or engage with licensing changes I highly recommend you work with a lawyer. Guessing or going by "legal vibes" in this space adds unnecessary risk.

think of why someone could pay for something you offer free :

- have some control over you : integrate feature, prioritize you backlog, influence the roadmap...

- have confidence that the project will be maintained and won’t be abandoned

- direct support from the maintainer

- visibility/marketing

- ...