Many developers have created Open Source packages and tools to help them do their work in a better way. Those developers usually work for other companies as employees or consultants, so they earn salaries or consulting fees.
One way to make more money is to create commercial versions of the your Open Source packages or tools. Such commercial versions can offer additional benefits like private support, regular updates that are provided to paying customers with greater priority, or even hosted versions of the packages provided as APIs.
You can charge you customers a subscription fee that costs an affordable amount of money, so many developers can pay a monthly amount that is fair for them to pay and they can enjoy the additional benefits that paying customers may have access.