Unlocking thru online activation setup

Hello I have a ready to go plugin and the only thing I have little idea how to do is providing online activation for it so that I can have the option to sell it. I have followed the Unlocking your plugin thru online activation tutorial, but am stuck in the generating security keys section. is there a better way or a good tutorial out there on this topic. thanks

The key generation in the tutorial just runs openssl from a terminal. Do you have openssl installed on your system?

Thanks for answering I have more or less figured it out now.