yes, thats the problem, there's a lot of plugins without license, which makes their usage in commercial projects questionable.
regardless of your choice of license, you should include the rot.js license in the files from rot library you distribute, as currently you're not respecting the rot.js license which states that the license text should be included in any distributions. ( also be careful that licenses are compatibile
nevertheless, a great plugin, cant wait to see a stable release!