You don't have to make a variable, but if you don't, you might get slight lag after playing a long time.
To bring up the Variable chart, you must open the trigger editor.
1. find "edit" on the top, click it and find "variables" on the bottom of that list.
2. press ctrl + b
3. click that yellow x-shaped icon right after the undo/redo icons at the top.
After its open, create a variable and name it Temp_Point and change the "Variable Type" to "Point" and press ok.