Legally, you must have a valid product key. Keys are tied to the version:
Since Office 2010 is end-of-life (EOL), Microsoft no longer provides security patches. If you connect a PC with Office 2010 to the internet, you are vulnerable to: Legally, you must have a valid product key
When downloading the bundle, you are getting more than just Word and Excel. The full stack typically includes: Legally, you must have a valid product key