I do not have such experience, so you can skip my comment, if you wish. But there is the Dropbox, Github, Bitbucket and many others' model: tolerate the mass o

I do not have such experience, so you can skip my comment, if you wish. But there is the Dropbox, Github, Bitbucket and many others' model: tolerate the mass of completely free users, have no ads, balancing it with paid accounts with extended functionality, more storage space, etc. From my humble perspective it is a tricky and unstable business model, but it obviously works for many.