Hey @jaylinb,
Thanks for posting on the community. Are they trying to track accounts for a related business or a totally separate llc?
If your client is using QBO, they can only have one company per subscription. I've heard of some users creating "classes" to separate expenses/income/asset accounts for the different entities this way, but I'd recommend against it. This type of tracking gets very complicated, messy, and can't utilize the built-in tax/1099 features.
As their bookeeper, you can get them a big discount if you buy their QBO subscriptions in bulk. You might want to check out the 5 for $5 program. Hope this helps!