Demo fonts include an English alphabet, most numerals and some punctuation. Just enough to get a feel for the font before you decide to purchase. OpenType features and special symbols are not included.
Demo fonts are for internal testing purposes or for student projects only. They're not for personal use projects. You can use the fonts to create graphics, link the webfont to webpages using the @font-face selector in CSS files, and embed the Font into applications or eBooks. If you're testing on the web, make sure the site isn't publicly accessible.
To get the demo fonts, choose any Typodermic font you like and follow the Fontspring link. At the top of the font page, you'll see a "Download Demos" button. A Fontspring account is required to get the demo fonts.