Can't open an .eml file

Sorry if I'm in the wrong post. There is an .eml file of a past software order that I very much need to open to access the purchase information/license code, as the EaseUS software has disappeared from my system and I want to download it. I emailed EaseUS and gave them the license code for the version I had purchased, but their email reply offered only trial version; I've paid for the software. I've studied searches I've made, "how to open an .eml file" but frankly, the solutions are not understandable or clear to me. The program has diappeared from my system, but I don't want to have to purchase new EaseUS software. Thanks ever so much for any suggestions you all can give me to open this .eml file. ellenc