Invoices can be created for individual students, or for every student in your Studio (Batch Invoices). Typically, invoices are created for a month at a time; that is, you create the invoices near the end of the current month for the transaction in the next month. For example, create the August invoices toward the end of July and set the invoice due date for August 15th.
Studioware also tracks the status of every invoice. The most important status is "PIF" which is Paid-In-Full. When reviewing the unpaid invoices, the "Outstanding Invoice Report" will show you all invoices that have not been paid. You can follow up with an invoice reminder email, phone call/text, or add a late fee to the invoices.