My MAC seems to be operating slowly is there a memory upgrade that can be installed on my 21.5 inch late 2013 MAC

Welcome to the Apple Support Communities.

I believe we need to proceed with an EtreCheck report. EtreCheck is a useful App to diagnose and identify issues, both hardware and software. It is trusted by many users. Please follow the steps outlined below:

1. Navigate to: https://etrecheck.com and get the free version of EtreCheckPro.
2. Download it. It is a free and trusted app. It is often recommended here on Apple Support Communities. 
3. Open EtreCheck, and before running the report, be sure to check “Allow full Drive Access” at the bottom of the EtreCheckPro window.
4. Run the report, and put it in a post, as shown here: https://discussions.apple.com/docs/DOC-250000211. We will then examine the report for issues in your Mac.

Jack

Your 21.5 inch Mac has its RAM permanently installed and is not upgradeable. I second the idea of running the EtreCheck app and getting its report. I am guessing that it will show that you have an old, slow hard drive installed which is your problem. If so, installing an external solid state drive and installing the Mac OS on it will significantly speed things up.