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Do you want to know how to get the Trial Version or you want to check if you have license for ESM.
If you have license for CCS then ESM should be included in that.
However if you are looking for a Trial Version then

To obtain evaluation license, please visit the website: http://www.symantec.com/business/products/downloads/index.jsp. If you are unable to locate what you need, please contact the Sales folks. Their contact number can be found at the link:http://www.symantec.com/en/aa/business/contact_sales.jsp

Also check : https://www-secure.symantec.com/connect/forums/welcome-symantec-enterprise-security-manager-esm-forum