If you do not log into the server for 9 days, your base will be marked as abandoned. When this happens, an announcement is broadcast on the server. Your base is marked and a bubble appears around the base. Players are able to damage your base and kill you. They can loot everything within the bubble. If no one attacks it, the base will decay quickly.
Only 1 person authed on the base needs to log in and they do NOT have to interact with the base. So, if you know you’re going to be gone more than 9 days and don’t want to start over, auth a trustworthy player that will be on more often so your base won’t decay.