Hello Catherine Tran,
No, you have to do the work. Haha, just kidding.
If that is what gets you to exercise, then okay. Otherwise, there are numerous exercises to work your abs, just as well if not better, without ab machines. This is a personal preference.
Depending on the machine, there are positives and negatives, just like anything else.
You may want to do your homework before using and/or purchasing something in order to reap the benefit you are striving for.