Some legitimate "GPL Clubs" buy the Unlimited License and redistribute the plugins for a very small fee. While this is legal under the General Public License, you still won't get automatic updates or support .
Strictly speaking, JetPlugins are premium products. However, there are a few "work-around" ways to use them legally without a massive upfront cost: jetplugins license activation free work
Hackers modify the plugin’s PHP code to bypass the license_is_active check. This makes the plugin think it is activated. Some legitimate "GPL Clubs" buy the Unlimited License