It would if you shared what you've heard so that we can verify if the rules apply across the board? From what I have read, once you pay a one-time fee, you obtain the legal right to use a composer's music in commercial or personal projects.
Usage rights vary from one website to another. There are some that give you unlimited usage, while others give you a limited number of uses. It is confusing indeed. I think the best thing to do is to check their fine print.