Marketplace: Free isn't Free
The marketplace has apps that are labelled as free when they have a 14 day free trial... But they're certainly not free.
Maybe worth adding a Free Trial tag instead of Free. In the image attached, the first Facebook App is free but the others cost USD 60 per month.
This is an easy example but there are many others that require a lot of hours of prep and setting up whilst they do their best to leave the actual payment to the very last step of the set up process.
It's just misleading when it doesn't need to be. Hope this helps.