ISESteroids already saves your current command history, so when you relaunch ISESteroids, your old commands are still there. Simply type ArrowUp or ArrowDown in the console to browse your persisted command history.
Advanced Command History Search
To quickly find a previous command, we just added a new feature. It lets you easily find commands in your history.
In the console, simply type a word you expect to be in your command. Next, hold CTRL and press ArrowUp or ArrowDown.
This will apply a filter to your command history, and the console shows matching commands whenever you press the arrow key. The status bar reports details to the selected history item.
Note that the command history search takes the current command input and uses this as a filter. Make sure you keep pressing CTRL while you browse your history. When you accept a command, and then again press CTRL + ArrowKeys, then the new command becomes the filter, and most likely you will not find another match for it.