Will an LR4 help me?

We have 3 cats in a 3 story townhouse. We’ve lived here 8 years and for some reason one of our cats started peeing on the floor on the bottom level of our townhouse which is where the entry point are. We added a litter box down there because we could never get to the root of the inappropriate urination. Unfortunately, they use the litter box down there now as well as the two we have upstairs. However, the pee down there is like a territorial pee that is so intense. I can’t stand it anymore. No matter what I do it smells like horrible piss. We use a pellet system, but I’m desperate to try anything else at this point. We never have people over because I hate that right when you walk in the house it smells like piss. Will an LR4 down there help with the smell? I hate to spend the money and I’m scared it won’t make a difference. Thanks for any advice!