If you want people to actually be able to use it you'll need to put the license on Github, e.g. with GPL you need to supply a copy of the gpl, and should add headers to the file just to make things clear (See https://www.gnu.org/licenses/gpl-3.0.html ). Without clear licensing no responsible developer will touch the code with a bargepole. (GPL is a fairly safe first choice -- all improvements have to be rereleased as source code, and you can always switch to more permissive licences later should you wish.)