Trust in online platforms dealing with virtual goods

I hope this is the right stackexchange for this sort of question. Probably it can be more generalized, but I will explain it using my use-case.
I am implementing an online platform, where third-parties sell virtual goods to clients on a subscription basis. Let’s take for example ebooks as a virtual good in this case.
How can the third-parties trust my platform? How can they know that I don’t cheat with the number of subscriptions I report back to them? Do any solutions exist for this or some papers? I can’t possibly be the first with this kind of problem. The problem is I even don’t know what to search for.
Game theory is also the only tag which I could think of, maybe someone could edit the tags?

Thanks in advance