Did you read the instructions?
Numpad 9: 99 Token Currency - to use this, press TAB to enter the menu where
you can upgrade your suit (PRAETOR SUIT). Do not press this option until you
are ready to use it! Next, highlight an item that you wish to update
on the suit, and note the cost of the upgrade. Next, press this
option key and then purchase the upgrade. You have about 3 seconds
to complete the purchase and the option will toggle back off. Using
this you can upgrade the suit, even if you do not have enough
currency. Also, if you have the UNLIMITED AMMO option on, you may
also end up with 99 Tokens as well when you spend one.