Clients can fluctuate between free and paid users.
Now we want to add Basic HTTP authentication to our paid service. This is impossible to do for everyone, since we would take a serious performance loss checking for .htaccess files in the entire directory tree on every hit. I added this to the filter script and it works fine, and is only executed when the website is a paid one. The problem with this is I'm realizing how complex the .htaccess-based authentication scheme is, and I don't feel like coding the rest of it when it's already done.