Some companies will only use gems with a certain license.
The canonical and easy way to check is via the gemspec,
spec.license = 'MIT'
spec.licenses = ['MIT', 'GPL-2']
Even for projects that already specify a license, including a license in your gemspec is a good practice, since it is easily
discoverable there without having to check the readme or for a license file. For example, it is the field that rubygems.org uses to display a gem's license.
For example, there is a License Finder gem to help companies ensure all gems they use
meet their licensing needs. This tool depends on license information being available in the gemspec. This is an important enough
issue that even Bundler now generates gems with a default 'MIT' license.
If you need help choosing a license (sorry, I haven't checked your readme or looked for a license file), github has created a license picker tool.
In case you're wondering how I found you and why I made this issue, it's because I'm collecting stats on gems (I was originally looking for download data) and decided to collect license metadata,too, and make issues for gemspecs not specifying a license as a public service :).
I hope you'll consider specifying a license in your gemspec. If not, please just close the issue and let me know. In either case, I'll follow up. Thanks!
p.s. I've written a blog post about this project
p.p.s. Here's a list of the license names I've found and their frequenceis
I added the license field to our gemspec. However, we won't publish a new version on rubygems right now. It will wait the next release.
We will also think about displaying package's license on Gemnasium too.
Thanks for the suggestion!