According to CPANTS as recorded in my mail to the module-authors mailing list back on 24 March 2008 there were 9,920 distributions without a license field in their META.yml (or without a META.yml).

Today I checked CPANTS again and there are 10,235 such distributions.

I'd rather see this number shrinking than growing and it is very simple to do that. You just have to go to each one of your modules and update their Makefile.PL or Build.PL. Next time you release them they will already include the license field.

See how to add the license field to META.yml and META.json of a CPAN module.

See also my previous notes: Missing licenses on CPAN modules? and License of Perl Modules on CPAN