When I began developing a website for a nonprofit that had $0 for web development, I had to find a good subscription management extension that was cheap, preferably free. Akeeba Subs was the first subscription management extension that I found that was free. I have found myself needing to modify the views to fit the nonprofit's needs, but this is extremely easy to do. The documentation is well written, the forums contain many answers to common questions, but more importantly, the code is easy to read and understand. Like the other Akeeba extensions I've used, this extension is truly a joy to work with.