Does a contract need constant little amount of Gas to live on the blockchain...?

  • Could someone clarify how does live a smart contract on the Expanse blockchain?
    If some conditions of a contract are "running live", how does that work to run conditions live?
    And also if there are conditions running, there is a cost in Gas as I have understood, so you need to periodically send some Gas to the contract address to guarantee your contract is still "alive"?