Anchoring on a blockchain is a simple and cheap way to notarize documents and timestamp data. Authorization levels and ACLs offer limited protection against manipulation by those in charge or tasked to maintain the system.
The anchoring node indexes anchor and association transactions and provides an easy-to-use REST API. However, it's not required to run an anchoring node to anchor on LTO Network. You can use one of the client libraries to create an anchor transaction and broadcast that via a public node like nodes.lto.network.
The LTO node comes in several flavors. Anchoring nodes expose an HTTP REST interface allowing you to easily submit anchor transactions. The transactions are signed by the node and (thus) paid by the account associated with the node.