When the bar is fully red, the claim will last 60 days. This means your claim will currently cost a little over 4 silver each day.
From the relevant announcement post:
Click me!Claim Upkeep
As of right now claims require upkeep to the tune of 4s + (Claimed Area / 300)s per day. If the upkeep is not paid, the claim is turned off and the stone itself becomes possible to destroy. You can charge the claim with enough silver to last 2 months. Previously existing claims will be charged to last one month.
When you memorize people, you can give them a colour (ctrl+B to open Kin list, then click someone and change the colour). In your claimstone you can set different permissions for each colour. In your current settings, kinned players who are set to white will be able to do anything on your claim (we can't see settings for other colours).
this should generally
NOT be the case. Teach yourself to set no player on white. There are plenty of other colours, but white is the default colour: if someone has your homestead secret, they'll be able to kin you. They will then turn up in your kin list, white. If they know where you live, they'll be able to wreck havoc on your claim without any crimes being committed.
TLDR;
Don't give permissions to white people (man, that came out wrong)