/etc/portage/package.license

The  file Article description::contains definitions for per-package ACCEPT_LICENSE statements. Some packages will only be allowed to be installed by accepting its license. Licenses are stored in.

Example
In this case, at-least-one-of (because of the  part) the linux-fw-redistributable or no-source-code licenses must be accepted. To do this, create:

Format and examples

 * Comment lines begin with  (no inline comments).
 * One DEPEND atom per line followed by additional licenses or groups.