Ello was originally built as a private social network. Over time, so many people wanted to join Ello that we built a public version of Ello for everyone to use.
Ello doesn't sell ads. Nor doest the company sell data about its users to third parties.
Ello is completely free to use. Ello occasionally offesr special features to their users. If it creates a special feature that the consumer really like, one may choose to support Ello by paying a very small amount of money to add that feature to your Ello account.
Users never have to pay anything, and can keep using Ello forever, for free. By choosing to buy a feature now and then for a very small amount of money users can support the work and help make Ello better and better.