What is your end game? To have an exported HTML file, or are you just trying to get your content out?
If it is to just get content out, you can turn on the Text Pane Selector and view your memo in Preview (you’ll need to have the HTML template installed). In preview to a ⌘A to select all to put you memo on the clipboard. You can then copy and paste to email, word, etc.
You may find the training videos helpful: