Can you use Office for free, and when is a licence worth buying?
Free options exist, and they suit light use.
Office on the web
Free with a Microsoft account. It covers basic editing.
Mobile apps
Free on small screens, with limits.
LibreOffice
A free suite for your computer. Complex files may lose formatting.
Google Docs and Sheets
Good for sharing, weaker for heavy Excel work.
When to buy
You need the full Excel, macros, Outlook, Access or reliable compatibility with clients.
Why not pirated Office
Cracks are a common source of malware, and they break after updates.
Which paid option is cheapest long term?
A one-time licence, if you keep it for several years.