It is hard to justify unless you know you need it. IDEs get used on multiple projects. This license is per site. IDEs often have some kind of trial or at least you got to play with it on your friend's computer first. But "commercial use" could include testing it in your commercial application.

I prefer licenses that are based on how much something gets used. So, free if your site has small traffic or maybe free if the number of developers using it is small. That lets me use it in experimental projects or personal side projects (which may or may not make money and hence may be commercial) but not have to pay until the project grows large enough to be worth buying something like this.

I think the only library I've ever bought for a web project was $30 for a site license. It was when I worked at a company and multiple projects were going to use it and run from the same domain.