Once GameGuardian is installed, you can leave the app running in the background with a semitransparent icon that you can see on the screen at all times. When you run a game, you can open GameGuardian and select the process of the app you want to modify. For example, if you only have a certain number of lives in a game, you can use GameGuardian's hexadecimal editor to search for this number and replace it with any number you want.
Another one of GameGuardian's features is its ability to modify the app's internal clock and of the device itself to get immediate improvements in video games that normally make you wait a certain number of hours for a building to be built or to get your energy back. If you hold down your finger on the floating icon, you can increase or decrease the flow of time.
It goes without saying that this app, in most cases, is meant to be used to basically cheat at games. So, if the developers of the apps you use it for detect that you're cheating, you run the risk of losing your account. Don't say we didn't warn you.