Hello @dyoshizawa,
for these lower-end switches you have to use the WebGUI to check the hardware resource utilization.
The commands used on enterprise-class switches do not work on the 1200/1300 switches and to the best of my knowledge the CLI does not support monitoring hardware resources like CPU or memory.
Therefore, you need to login to the WebGUI and navigate to "Status and Statistics" --> "Hardware Resource Utilization" for a graphical display of hardware resource utilization including memory.
You can also add the "Resource Utilization" module to the dashboard so that you can monitor this directly from the dashboard view.
HTH!