Z:gnu-www-ja-selling-exceptions--866932-Selling exceptions depends fun/en

Selling exceptions depends fundamentally on using a copyleft license, such as the GNU GPL, for the free software release. A copyleft license permits embedding in a larger program only if the whole combined program is released under that license; this is how it ensures extended versions will also be free. Thus, users that want to make the combined program proprietary need special permission. Only the copyright holder can grant that, and selling exceptions is one style of doing so. Someone else, who received the code under the GNU GPL or another copyleft license, cannot grant an exception.