You can substitute bouillon cubes in recipes with broth, stock, or a combination of herbs and spices for flavor.
Bouillon cubes will get sticky and stick to the paper they are wrapped in if they are not used within a certain time, so yes, they do go bad.
Cornstarch can be used as a substitute for arrowroot in recipes.
Parsley can be used as a substitute for cilantro in recipes.
Coriander or chili powder can be used as a substitute for cumin in recipes.
Stock cubes, also referred to as bouillon cubes are small, usually individually wrapped cubes of dehydrated stock. They are available made from vegetables and meats, contain a small portion of fat and are usually seasoned with salt and other seasonings. Mixed with liquid in a recipes, they dissolve into a broth.
Paprika or turmeric can be used as a substitute for annatto powder in recipes.
Ground okra can be used as a substitute for file powder in recipes.
Vanilla extract can be used as a substitute for maple extract in recipes.
Butter or margarine can be used as a substitute for shortening in baking recipes.
Agar agar is a vegan gelatin substitute that can be used in recipes.
There are quite a number of various locations where one can find recipes that call for bouillon. Bouillon is a French broth, meaning that it would be used in many soup recipes native to France. One should try a French cookbook or a recipe website such as FrenchFood or FoodNetwork.
Quinoa is a gluten-free substitute for farro that can be used in recipes.