Aside from the VC funding that others have mentioned, being a publicly listed company means that there is a never-ending pursuit for increasing profits. Investors who buy stocks want to see a positive return. The problem with some tech platforms is that their product / service offering is already ideal, so their choices are to either spend money to innovative and build something new (risky!) or simply raise prices. Subscription pricing is ideal because it provides a consistent revenue base and allows the company to forecast what revenue is likely to be in the future.