Once you've built a product that delivers value, you'll start acquiring customers that silently pay the subscription and you never hear from them again. But there are also times that a user will reach out to you with some ideas about how you can make your product a better fit for them. If you can sign these users up as customers, you'll both benefit from the relationship you've formed.
I recently acquired two of this type of customer and it's made imdone a much better fit, not just for these awesome customers, but for all my current and future customers.