Can an open source project be non-free?

Question

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Let's say I have an open source product. But let's say I want to charge for the commercial use of this product, as well as for any commercial use of this code. At the same time, for personal use and educational purposes, leave the product free and open source. Is this even possible, or are they mutually exclusive? It is clear that there is piracy, it is clear that it is not possible to check programmatically whether it is for commercial purposes or not, but purely formally, so that if someone goes crazy in the region, then you can sue, is it possible to stipulate this somehow?

Answer 1

It may well. True, depending on what kind of product - based on this, there may be different models of monetization.
As an example - some game engines - the condition is the following - "if the income from a product created using the engine exceeds n per year - please buy a license." normal working model.

Answer 2

Yes, easily.
For example nagios.
Nagios Core - free and OSS - download, install, use if you overcome the configuration and are satisfied with the lack of a dashboard, an ugly face and the lack of graphs (which, of course, are screwed over the back, but sometimes they are driven).
Nagios XI - paid and very expensive. And there is already a configurator with intelligence, and a dashboard and charts, and whatever you like.

Answer 3

The free license cannot restrict the use of the product in educational, home or any other area.
In the free software world, people don't pay for the right to use a program. Although other forms of profit are allowed: support contract, server payment (if the program depends on the Internet), donations, certification (for the same government agencies, for example, no one will legally let an airplane fly on unknown software).
There is also an option to release the program under a permissive license (BSD, Apache, MIT, X11, etc.). They allow you to build a non-free product on top of a free, weak-willed product and charge people for the right to use the program. This is how Google Android, IntelliJ IDEA, Gitlab work.
There is another option with dual licensing. For example, OnlyOffice Community is released under the free GNU AGPL license, while the Enterprise version is proprietary. The main thing is that third-party committers (if any) give such rights, licensing changes on weak terms or withdrawing them.