If you're a student and you have a working ".edu.ph" school email, then microsoft offers it for free.
Otherwise, you can try using a MS Office activation script available sa Github (look for massgravel). Personally used it myself on all Windows PCs and encountered no issues. Open sourced yung script and madami na nagaudit so safe naman siya. But if you're still not comfortable, then piracy is the way to go (look for piratebay proxies) but this is way more risky if you don't know what you're doing.
If ekis sa lahat sa taas, then buy the license from Microsoft. Atleast this option gives you the peace of mind na safe lahat.