App running on a phone

So I bought my husband the HTC Desire 625, same phone as me. He has an icon on the top of his screen that's always on... I looked up running apps and don't know what Dlnamiddlelayer is on his phone. I don't have it. He did buy the phone from a person, not a store. Is it safe to delete this app? What does it do?
Thanks for your help. 😕