  We use a control framework to analyze the digital vendor's profit
maximization problem. The vendor captures market share by focusing costly
effort on post-launch product maintenance, which influences user perception of
the product and drives a revenue stream associated with product use. Our
theoretical results show necessary and sufficient conditions for product
maintenance to decline over a product's life-cycle, thus showing conditions
when Lehman's 7th law of software evolution holds. We also numerically
illustrate control paths under different market conditions.
