Premium Jam rounds let you access additional features in Jam mode. These are: 1. Race against up to 9 other players at one time. Hit the icon with the helmet (#1 in the screenshot below) to change how many riders you race against. 2. Use the track preview feature. Hit the track preview button to see the layout...
If you purchased Premium Jam rounds, but are not able to use them please try hitting the restore purchases button in the settings menu (shopping cart icon). In most cases your purchase did go through, but it's a server sync issue causing the problem. Usually it resolves itself after a few minutes. If for some reaso...