what is the policy on using assets that came from the asset store

well if i wanted to make a game that would sell for a dollar, and used a 3d model from the asset store would i have to pay them money for that or could i use it for free as long as i dont state anywhere that i made it.

If you purchase assets from Asset Store then you can use it in your games ‘made with Unity’ and sell that game.
For free assets also you can download and use those assets in your game ‘made with Unity’ and sell that game.

Read Unity Asset Store EULA for more details.