How can you use multiplicative identity property in real life?

Answering the question in general terms:

1. Since we are taught the property at an early age (initially without identifying it formally as a property) , our use of it generally goes unnoticed (for example, when it occurs in a multiplication problem involving the digit 1).

2. When solving algebra or arithmetic problems or proofs, if we can reduce a factor to 1, then by the property we can eliminate this complicating factor.

3. Having identified this property, we can create new mathematical systems within which we can then decide whether or not to include that property.