>That is $100K/year for 10 years = $1M productivity improvement for $10K! There are two parts of the equation here: [His business] + [Your software] = [Value].

>That is $100K/year for 10 years = $1M productivity improvement for $10K! There are two parts of the equation here: [His business] + [Your software] = [Value]. Your software alone, meaning when it is not in use by his business, is not worth $1M over 10 years. It is worth $0. His business is what gave your code value.