Hi @Kalee Guzzo , i'll glad to give you information about users limit in quickbooks desktop. QuickBooks Desktop Pro allows up to 3 users to work in a company file simultaneously. Though you can set up a multi-user network, still, three users are allowed (per license) for them to access the company files. Here is the article about multi user network.
If you want to purchase another user license, just follow the steps below:
Click Helpon the menu.
Select Manage My License.
Tap Buy Additional User License.
Choose the option on how you want to purchase the new license.
And here is the article about add user license. Comment back, cheers.