How to determine the type of free-licence in the assetstore?

I'm learning Unity and I'm creating a game for my kids. For this purpose, it realy doesn't matter what type of game-art I use. It's a non-commercial, learning project for me. And chances are big it will never be seen outside of my house :). So at this point, I'm using the Unity Sample Assets from the AssetStore, and I've drawn some of my own sprites.

But what if it turns out to be a nice project, and I want to publish it (either to the play-store or via some other way as a windows-game?)? Can I still use the Unity Sample Assets?

How do I know, looking at (at this moment) free assets, whether I can use them in a commercial project?