not exactly. More like you offer a base line service (for example sake lets say for free), then you offer individual feature add-ons at a cost. That way, rather then paying x$ for upgrading say, professional to ultimate and getting a bunch of features you don't need, and the single one that you do, you buy exactly what you want, and no more. Also could provide a way of priming your users to submit features that they would actually want to pay for.