Buy credits and use them to buy things in-game! This helps give you discounts so for example, you can go from rank 2 to 5 at a discounted price!

500 Credits
5.00 USD
1,050 Credits (+5% Value)
10.00 USD
2,200 Credits (+10% Value)
20.00 USD
3,600 Credits (+15% Value)
30.00 USD
8,600 Credits (+30% Value)
60.00 USD