As long as the paid version removes this advertising (picks a random movie for instance) and you're up front with the fact that the "free" version will include

As long as the paid version removes this advertising (picks a random movie for instance) and you're up front with the fact that the "free" version will include sponsored content in the conversation [1] then I see no problem at all. I'm sure everyone knows by now that if the product is free, "you're the product". [1] I wouldn't even care if the conversation went off on a massive tangent temporarily to include the advert. The point is that not everyone can afford to pay for such a service, and advertising can solve that issue.