Regular, predictable monthly income is just a better model for businesses than irregular large one off purchases. Customers generally don't mind so long as the

Regular, predictable monthly income is just a better model for businesses than irregular large one off purchases. Customers generally don't mind so long as they can cancel easily if they find they don't need or want the product. Plus, you can't really buy a "web app" with a one off purchase and much more software is developed as web apps nowadays.