Every product contains 2 order form links. The order form which will show the simple prices you create and the Freebie link which allows someone to purchase the product free of charge and without putting in payment information.
The links for these order forms can be found in the side bar of the product. Their names are displayed in a white box, if you click on that the order form will open in a second screen. Or if you select the clipboard next to the order form name the URL will be saved to your clipboard and can be pasted.
You can reset a freebie link, making the old link invalid for anyone who has it.
To do this, select the red link before the freebie that says "reset freebie link"