First 12 hours for free, then paid

Hello,
I tried something like this:
First 12 hours free of charge, after that the cost will be added for 10 scrap. It does not seem to work that way !
Maybe a good feature to add ?!
   

"Protection levels": [
      {
        "Rank": 1,
        "Online protection percentage (0-100)": 0,
        "Offline protection percentage (0-100)": 100,
        "Hourly cost per authorized player": 0,
        "Hourly cost per floor": 0,
        "Hourly base cost": 0,
        "Cost per damage protected": 0,
        "Max protection time (hours)": 12,
        "Delay for offline protection (seconds)": 60,
        "Delay after taking damage (seconds)": 10,
        "Damage resets timer when owner is offline": true,
        "Allow tugboat protection": true,
        "Allow barge protection (requires Barges plugin)": true,
        "Founder Limit": null
      }

      {
        "Rank": 2,
        "Online protection percentage (0-100)": 0,
        "Offline protection percentage (0-100)": 100,
        "Hourly cost per authorized player": 10,
        "Hourly cost per floor": 10,
        "Hourly base cost": 10,
        "Cost per damage protected": 0,
        "Max protection time (hours)": null,
        "Delay for offline protection (seconds)": 60,
        "Delay after taking damage (seconds)": 10,
        "Damage resets timer when owner is offline": true,
        "Allow tugboat protection": true,
        "Allow barge protection (requires Barges plugin)": true,
        "Founder Limit": null
      }
    ],

Is this something that You would consider ?