I vaguely described this in feedback. There should be a status bar that shows what special effects you currently have applied. The bar should be like the quick tap background when you pull it up.
On this bar there should be a number of things that show up if you bought them. if you don't have them, maybe a dark circle or just an empty space could be there instead. Or, a gray version of it to show it hasn't been bought.
First icon (Ammo Box): Unlimited Ammo.
Second Icon (Revive Flask): Revive (And a number to show how many days/hours left. Example: 2D is two days. 23H for 23 hours.)
Third Icon (The letters "VIP"): VIP Purchase.