Where is declared that Ubuntu is free for users? I mean officially declaration where Ubuntu mention that desktop version is free to use, not commercial.
3 Answers
It says so on the main Ubuntu webpage. A strange place for it, granted, but there you go:
Ubuntu is free for all, and open-source, but you can buy a premium customer service to Canonical, and some advanced software are not free (but still open-source).
On the about pages you can read about everything regarding licensing free and OSS (open-source software):