I found that the Non-GNU ELPA didn't show the license of the package on
it.

example: https://elpa.nongnu.org/nongnu/zig-mode.html

GNU ELPA is a part of Emacs, so the packages on it should be GPL3+, but
the package on Non-GNU ELPA should use different license like MIT Expat,
GPL2, LGPL2.1 etc. (correct me if I'm wrong). Can we add a line to show
the license of these packages on website?

BTW, the website says it licensed under CC BY-ND, which is not a free
license IMO violates the spirit of GNU. Is there any reason prevent us
using CC BY-SA or GNU FDL?
-- 
Retrieve my PGP public key:

  gpg --recv-keys D47A9C8B2AE3905B563D9135BE42B352A9F6821F

Zihao