You can host a dedicated server, but because of how Steam works you will not be able launch the game again to join it. Unless you have a normal Blockland key (less than ID 60000), you effectively can't host a dedicated server.
If you still want to host a dedicated server, the main option is to
Buy a normal Blockland key to host with.
Or, alternatively, you can buy hosting with a rental key from
BlockNet. There unfortunately isn't a solution that doesn't cost money.
