When your body breaks down dietary protein into amino acids, any amino acid lacking a complimentary amino acid just hangs out in the pool until a complimentary amino acid comes along to complete it. Then they join up and get to work doing good stuff in your body. As long as you eat a varied diet, the essential amino acids in the food you eat will find each other in the pool. Say you eat a handful of peanuts in the early afternoon. Later on you have a handful of whole-wheat crackers.
Peanuts are low in the amino acid methionine.
Whole-wheat crackers have a lot of methionine, but insignificant amounts of lysine and isoleucine. Of course, you could eat a peanut butter sandwich on whole wheat bread and be done with it, but the point here is you don't have to eat complete proteins to reap the benefits as long as your diet is rich in a variety of healthy foods like whole grains, legumes, vegetables and fruits. Now that that's out of the way, let's talk about how much protein you need in your diet. The chart below is what the U.S. government recommends as the average daily requirement of protein. Of course, every person is different, both biochemically and in their lifestyle choices, activity level, health, etc.