Just by chance, I came across a seemingly unrelated (and a bit old) article which lists pros and cons of various package managers ([0]). According to it, PyPI (Python), RubyGems (Ruby), NPM and Bower (JavaScript) and Lein (Clojure) allow packages without any explicit licensing info into their repositories. That's almost all major package repositories!
Since those packages would be proprietary, I would assume they allow packages with explicitly proprietary licensing terms as well. [0]: https://blog.versioneye.com/2014/01/15/which-programming-language-has-the-best-package-manager/
