Client accounts
Clients & invoicing is part of the Business tier. Create a client account, attach it to jobs (or import it as a column), and every delivered job for that client becomes billable work.
Invoices
Generate an invoice for a client over a period; it lists the delivered jobs at your billing unit (per delivery, per stop, per route or per order, from your preset's default). Pickup legs of paired work are not double-billed. Auto-invoicing can generate on a schedule, and clients can receive a daily summary of their deliveries with an unsubscribe link.