On the thirteenth day of each month, purchase a minimum of 25.00 ($USD, $AUD, or €-Euro), and you can claim a free 13.00 credit as a an additional bonus.

Just open the Liberty Slots cashier on the thirteenth day of the month, choose to purchase the required minimum of 25.00 and when you are presented with the list of available bonuses, select the ‘Liberty Lucky 13’ option. Once your purchase is confirmed, you will have an additional 13.00 worth of bonus credits in addition to your deposit.