Freelancers expense a dozen subscriptions — proposals, contracts, invoices, time tracking — against irregular income. Owning the tools outright removes a whole line of fixed costs.
The tool this job usually means renting is Expensify, at $5–$9/user/mo — roughly $60 a year, every year. Snapreceipt does the job for a one-time $19 — running locally on your own machine.