[naberhausj]

There is pretty much a hard limit on how much protein you need to intake. Often you'll hear one gram per pound of bodyweight as a rule of thumb, but in reality that is actually the ceiling. At the very most you need one gram per pound of lean body mass, not including fat (and most people are at least 15% body fat, even more for women).

Basically, the only way to know if you need a protein supplement is to track your macros. That means logging everything that you eat throughout the day. Personally, I eat lots of meat, and only need a protein shake occasionally. Before I started tracking I way over-indexed on protein. That's not necessarily a bad thing, but it was a waste of money (carbs and fats are both cheaper).

Additional protein won't hurt you, but it's not going to increase muscle growth. Especially not without hypertrophic exercise.