If you're paying for a subscription, the company might sell your data. If you're using a commercial service for free, they are certainly selling your data.
Having said that, you're right to be suspicious of commercial services, even that you pay for. Someone can found a startup with a strong commitment to customer privacy and the best of intentions, but a few acquisitions or near bankruptcies later, those commitments will go out the window.
If you're paying for a subscription, the company might sell your data. If you're using a commercial service for free, they are certainly selling your data.
Having said that, you're right to be suspicious of commercial services, even that you pay for. Someone can found a startup with a strong commitment to customer privacy and the best of intentions, but a few acquisitions or near bankruptcies later, those commitments will go out the window.