What are some real life uses of Stoichiometry?
If you work in the laboratory and/or manufacturing plant, it can give you the exact amount of reactants needed in a reaction or the exact amount of products that can be yielded from a reaction.
But if you are asking for more "practical" (as in daily, normal, layman's) applications, I can't give one to you.
Stoichiometry is basically applicable for all manufacturing plants/productions since it eliminates the need for "trials-and-errors" just to produce the desired amount/quantity of the desired product with a given known quantity of reactants.
This, in turn, minimizes the potential material and time wasted in any manufacturing plant, which then lowers the production/operational/overhead cost of any company, which then affects the pricing of goods in the global and local market, which then affects your daily budget.
Hope this answers your question.