Shop
Invoices do not need Microsoft 365. They do need a clean install.
A three-person shop can live on free Writer and Spreadsheet. Payroll macros, bank CSVs, and a supplier’s USB “setup” are how shops get hurt. This site is an independent handbook and is not affiliated with Kingsoft Office Software Corporation Limited.
Sensible stack
Official desktop plus phone scanner. One person owns the Kingsoft account if you use Cloud. Export PDF for customers who should not edit prices. See collaboration.
Do not accept a USB installer
Ask the supplier to send a document, not a program. Fetch WPS yourself from official channels.
When to pay or leave
If ads embarrass you on a client call, Premium or Microsoft is cheaper than looking sloppy. If VBA runs the business, you already know the answer.
Backups
Cloud quota is small on free plans. Export PDF for customers. Keep XLSX invoices on a drive you control. A USB from a supplier that also contains “setup.exe” is two gifts, and only one of them is a document.