Hi, thought I'd share what she wrote to me when I asked the same thing! Hope it helps!
The protein shake I use is whey protein powder mixed with non fat milk (Gold Standard Whey Protein Powder) . You can add healthy items to it if you like but I usually don't before or after a workout because I want it it to digest quickly and feed my muscles.
Yes, you can have protein shakes anytime, even if not working out, but be sure that you do not have too much sugar or sodium added in as then it becomes a less healthy and defeats the purpose of a healthy snack.
Some people use shakes as meal replacements but I do not, unless I have no other choice. I honestly feel that nothing replaces the good health and nutritional value of clean, healthy, nutrient dense food. Just watch your calories, portions, fats (and types of fats) as well your carbs and sodium content and you will be in a good place.