There isn’t one license agreement that covers all my fonts; the agreement varies from distributor to distributor. Always refer to the agreement that came with the fonts. If the fonts didn’t come with an agreement, you should track down a new version.
Reading license agreements is nobody’s idea of a good time but the following might help you make sense of it all.
Sometimes you’ll hear the term “desktop license”. It means you download the font, install it in Windows, OSX or whatever and use it in applications to make stuff. While there are some differences between desktop license agreements, there are some things they always allow.
A desktop license will always allow you to use the fonts to make logos, web graphics, business cards, t-shirts, posters and signs. You can use them in paper books and magazines. You can use them in movies and television. You can embed them in PDF documents in non-editable mode.
Free vs. not-free
There’s no difference between a license agreements for free fonts or “pay” fonts. The same commercial use is allowed.
Web, apps and e-books
License agreements have restrictions about embedding. If you’re not embedding, the desktop license will cover it. If you’re embedding, it probably requires a different type of license.
Embedding means including or encoding the font data into a product.
Suppose you’re making an iOS game and you use Photoshop to make a title screen using one of my fonts: that’s not embedding. Let’s say you want to show the player’s score and you need to encode font data into the application: that’s embedding.
Suppose you’re making an e-book. You’re using Illustrator to make the cover and all the fonts are converted to outlines. There’s no actual font data being embedded in the book: that’s not embedding. But what about the text or the chapter headings? The fonts probably have to be embedded.
Now suppose you’re making a web site. If you use Photoshop to create the gif, jpg, png, or svg of the site header; that’s not embedding. But what if the font is used for text or headlines? That likely requires embedding.
More on embedding here.