It depends. Look on the terms they gave you if they made you sign for it. Best thing to do is contact them and simply ask. You'll feel super better when they say, " no....you can keep it." Hey think of it this way, if they say yes, you need to give it back, you don't want to get stuck with a bill. Trust me, just save your self the trouble.

Example: in the radio and TV business some times show hosts get contracted endorsements, like New phones, ipads and in some cases a new car so they can talk about the products on air. Sometimes its short term and in some cases it long term. One of my close friends got a new iPhone 5 through verizion for a on air promo, so he can talk about how much he loves it, he got so attached to it when the promo ended, he didn't want to give it back. Problem was on the terms he signed for mentioned he would have to pay the full price if he didn't turn it in. $765 was the amount the station deducted from his check.

Usually it doesn't, but the company would ask you write some test report for the product you got.

If the company has asked it back then yes you have to return it because you are testing their product. Otherwise if the company has many made then they don't usually ask for it back.

If that is the terms the particular company states, it's going to vary depending on the company, be aware product and secret shopper scams are quite common, you may have to pay for the typical product that a survey asks about