For anyone interested, I noticed that Dyalog made their proprietary implementation of APL free for non-commercial use just recently [0]. I suspect this change might have been in reaction to an uptick in traffic to their site from this other APL HN post[1] a bit more than a month ago (there's some good discussion their as well).

[0] http://www.dyalog.com/ [1] https://news.ycombinator.com/item?id=11963548