why Custom metric filter will get deleted after 14 days?

i created custom metric through cloud formation template but it will get deleted after 14 days. so what is solution to retain it for longer time or as a never expire.
sample syntax for creating custom metric-

"MetricFilter": {
        "Type": "AWS::Logs::MetricFilter",
         "Metadata": {
            "Comment": "Metric Filter for /logGroup/TestInterval logs on specified filter patterns."
        },
        "Properties": {
            "LogGroupName": "/logGroup/TestInterval",
            "FilterPattern": "Error",

            "MetricTransformations": [
                {
                    "MetricValue": "1",
                    "MetricNamespace": "MetricsTest",
                    "MetricName": "ErrorTest"
                }
            ]
        }
    }