I do understand that, but currently my open source projects don't bring any monetary benefit at all, and my user base is too small to provide enough donation to

I do understand that, but currently my open source projects don't bring any monetary benefit at all, and my user base is too small to provide enough donation to support the development. So under this circumstance, any payment is way better than none payment. Plus, I also designed the system in such way that it allows me to vastly extend it's functionality based on the same base code. So in theory I could make a big enough feature-gap between the two. > On top of that, your main audience consists of people who really prefer not to pay for software. I thought about this as well. But doing a pure close sourced product is unlikely to cover these people too. Sure, making the product open source might convert some paying users away to use the open source version, but at least I earned the trust of these users (and hopefully made them happy), still not a bad out come from the open source perspective :)