Ask HN: How to protect myself from licensing lawsuit?

Hello. I created saas application that lets people stream video content. Everything runs on hetzner cloud and it's billed on my name.

I have a client, that streams music clips on tvfestivalmusic.cz. He claims, that he has all required licensing solved.

Does someone have an idea how should I protect myself from unexpected lawsuits, when some of my clients wouldn't have required licensing solved?