It's a 32bit and from an old version. Perhaps they don't want to annoy their paying customers? In this way they get more information from you. I guess it's good for their marketing research. Hopefully they would conclude that it would be better to make the software more freely available.

I'm not sure how big the market is for them or related array language. Seeing J became essentially open source, and kdb+ released their 2nd grade 32bit for non-commercial use too, I guess the industry is shifting toward more consulting/training services.

It is mostly a question of inertia; we've been busy making sure that our customers have what they need, and continue to be willing and able to fund our R&D efforts, since 1983. We agree it is time to open things up a little, although FOSS remains impractical at this point in time. The free non-commercial (but "registered") release of v15.0 is the first step. Later this summer I hope we will make the un-registered version available on more platforms and probably a bit less annoying too / Morten Kromberg (CXO, Dyalog Ltd)

The danger of people being interested in their product without them being aware of it.

Maybe it's an homage to Bill Gates who campaigned so hard for using intellectual property laws to protect closed source software.