Yes, it means they don't expect fast takeoff in the next year, but we already knew that.

Having revenue from their free users might can just be a way to make it more sustainable. And/Or make fundraising easier from investors (which has immediate benefit).

Seeing the message "you're reached your limit..." makes free users switch to other AI providers, and ads are a way to fund higher limits. Their prime competitor, Google, has ad income from users so has an advantage.