There's a reason Lydia babbles onward without giving the other girl a chance to actually answer her and it's because she wants to force Katniss to let the idea percolate before she tries to make a decision one way or the other. Hopefully, she thinks, she's been successful at that because Katniss moves on when Lydia does. She realizes belatedly that she probably shouldn't have assumed that the other girl knew what royalty fees are; most people their age don't. Lydia's nearly always been the exception to the rule when it comes to things people in her age bracket know.

"Ah, okay, so royalty fees are usually a quarterly thing, but I'll try to make it monthly for you instead. Basically, it means as long as we keep using the song, you keep getting paid. For every month that I've used the song in a commercial, even if it's just one, I'll pay you five credits for the right to keep using your work. Does that make sense?" she asks, lifting her eyebrows in sincere question. Lydia wants to make sure that Katniss understands and if she doesn't, then Lydia will break it down a little further, somehow, because it's no good to have someone agree to terms and conditions they don't understand. It feels cheap and shady to Lydia, so she's not going to let it happen here.

"If I stop using the material, then I stop paying you, but if I continue to use it, you continue to get paid. That's pretty much all it means in this context."