Why does what "work"? "Work" how? To start, how did you develop this formula for the "lifetime value of a customer"? What was the reasoning, and what data, etc, went into your development?
Also, what do you mean by "Retention rate: 50%"? Does this mean that your data shows that half of your customers return within one year of their first purchase? What is the meaning of "All retention after first: 75% to infinity"?