So under Licenses is how many times its been downloaded? Or does it only count when someone adds it their cart even when its free?

As far as I can tell, the number of licenses is strictly that - the number of projects using that addon / theme.

However, the number of actual downloads would be useful too, which I'm sure would be quite different than what's displayed for the number of licenses.

Thanks; I hadn't discovered that!

For me, it would be encouraging to see the total number of downloads (and ideally installations) of free add-ons because, if the number were significant, it would motivate me to develop more.

Would be nice for users to see this to!

I did a little experiment with my free add-ons.
If I use the download link the number of licenses doesn't change
If I use the cart and checkout, the count in incremented even if I don't assign the license to a project

I suppose that means that numbers we see for free add-ons are not actually that representative.

My free Social Icons Reloaded add-ons for 5.6.x show 6079 licenses. I wonder how many more downloaded directly and were not counted.

@AliceTr I sometimes think like you but I'd be curious to know what your stance is on this. What benefit do you see coming from showing those numbers?

A sure way is to skip the marketplace stats and embed an image in an addon that is rendered from your own server and track image requests. @goutnet created an addon for 5.6 that would serve and track images.

You have to be careful about doing such. Some users may get upset.