This is the one that you can't use for commercial projects?
And you know what? It was true. We changed the licensing to MIT for most of Opa (http://opalang.org), but maybe a bit too late.
If you don't want to do this, you need to get an enterprise license, which does not neccessarily mean to buy one: There are other options as well (sponsored development, …).
For details, please contact us directly using hello@thenativeweb.io
PS: I'm one of the core developers of wolkenkit.