1. Ads
2. make the free version of the service thats highly functional on its own and that make the REALLY cool features something you have to buy. I much prefer it if websites or apps just had one-time purchases rather than forcing me to pay rent money every damn month just to have a sparkly font color over my name.

Some products do this thing where you help out with certain stuff while using it, they give you coins that allow you to engage with more stuff. Voice.AI is like that, if you activate it in settings, it lets you use your pc as a way to train the AI once its idle in exchange for coins