From the article: "there is a premium subscription available that gets rid of the ads and promises faster speeds. In the U.S., this will cost between $12 and $14 per month, depending on the platform."

So unlimited free use, but restricted speed and injected ads. Not horrible, but I'd definitely read the T&C very carefully, I didn't see any mention of what logs they keep.

Whoops, how'd I miss that :/