[vhanda]

It doesn't. Neither does the website.

An article from Yahoo [0] says it's "$29.99 per month or $167.99 per year", but they don't link to a source.

[0] - https://au.finance.yahoo.com/news/duolingo-launches-subscrip...

[Balgair]

Woah, a dollar a day. That's a lot to ask from an otherwise free app. 3x the current price of a paid version