On rare and special occasions we may release premium boots to purchase that are permanent once owned. Usually this will include a trial first with an option to purchase after.
Boots can be worn in training or during matches, remember to equip the ones you want. Certain boots affect your scoring depending on their stats. You'll see if a boot you are wearing has any effect on your football levels if you see orange blocks on the stats bars. You'll also see how long of a trial you have left.
Remember, Training costs less trial points than matches.