1. $10 for GET request and ten license-domain pairs. For one project. $50 for ten projects and 100 licenses per project. Too pricey for small amount.
2. Nothing stops user from simply removing qeys.js from a page.
3. Functions in your js file are called "v" for validation, "iv" for invalid license error and "vv" for setting validation cookie. They can conflict with other similarly name functions from other parts of your customers's JS.
4. You set validation cookies on the client side. You literally have a code to bypass your system in your system.
5. User interface may be much better. There's too much hassle in setting up multiple keys. I need to switch between pages to do it.
Conclusion: your software isn't good, your prices are high. Something like that can be accomplished in one day with a couple PHP scripts tied to MySQL database with lifetime control over it. Everybody who needs it most likely are able to implement it themselves. You need to put more effort in it and polish it more to make it really attractive for others. It's a nice job for "Intro to Webdev" course project, but not for actual product someone will pay for. I don't want to offend you, but that's what I actually think as a guy with some teaching experience.
Shameless plug: I can develop similar (or better) webapps and now looking for projects. You can hire me. You may find me in Telegram with the same username I use on HN.