MySQL: normal CPU Utilization but I’m running out of memory. Should I get worried?

I’m running a heavy python script in a EC2 instance. This script is inserting tables (financial reports) to a MySQL server. There are lots of tables, the total amount is 240.000 tables. I started the python script 1 day ago and these are the stats of MySQL server. CPU Utilization / Memory As you can see, cpu utilization seems normal but memory has gone down since the script started running. Note that I’m only running this script, there is no other work for MySQL. How can I maintain the memory stable?