no it does not have to be plugged in to use. this is a portable pen vape for oils. It is like the V1 omicron, but with pass through charging. so you can use it on the go with the built in battery or (if your battery is low but you wanna use it) you can plug it in and use it WHILE it is charging.
the unit works fine for sure, i just didn't get into the pen vape style.
better for you cause you can snag a steal of a deal on one... they run $90 brand new and that doesn't include shipping.