The technology involve here is common place, I inspected the code and it's based on jQuery to detect the "mouse leave" document trigger and other easily attainable methods to display the modal, process the form, etc.
To all, I ask you to think about something: The entire tone of this thread is making a precedent here on the forum which is disturbing to me, pardon me being so blunt. It feels more like a sales pitch and marketing than a means to share design, development for the web which is the purpose (and name) of this forum. Especially since the link, and the OP's comments, are all about subscriptions and money.
I don't intend to be a bummer or cut into another man's pocket, and I am not a moderator here. I am a long time user who feels this kind of post is less about tech. This is not a personal attack against the OP, I'm not asking it be removed nor am I saying anything negative about the actual product. I'm only referring to the context of this forum and wondering if this is where we want it to go in the future?
(Rhetorically asked, replies not expected nor desired, don't want to hijack the OP's thread entirely)