There are actually two upgrades available. The first is called the Borders Add-On Pack and the second is the Frames Add-On Pack. The Borders Pack will give you added features to change the border color, size, texture and round the corners. These features are available from the toolbar at the top of the main collage creation page. If you have this toolbar, then you have the Borders Pack.
The Frames Pack unlocks all of the 160+ collage layouts. You can always check the email receipt that Apple sends to you to see which pack you have purchased.