A chance to try something out for free? What have you got to lose?

If you’re interested in a particular product or service, trying before you buy might seem like a no-brainer. But what starts as a free trial , or for a very low cost , might end up costing you real money.

The Federal Trade Commission, the nation’s consumer protection agency, wants you to know that some companies use free trials to sign you up for more products — sometimes lots of products — which can cost you lots of money as they bill you every month until you cancel.