func EnableMem() {
	sm.Add(mem.ServerMetrics)
}
EnableMem start to mark metrics to memory monitor system.
package aggregate
import (
	"github.com/fatedier/frp/pkg/metrics/mem"
	"github.com/fatedier/frp/pkg/metrics/prometheus"
	"github.com/fatedier/frp/server/metrics"
)