Fonts are usually licensed like any other piece of software, so the terms will vary. Generally, though, I'm not aware of any major foundries that would allow their fonts to be redistributed in commercial software under the same license sold to an end user. The licenses are usually restricted to a specific number of installations or users -- for instance, I believe Adobe's standard font license restricts installation to a single computer at a time, so you couldn't even share them with another designer, let alone redistribute them in an app. Occasionally (but not always), the license will give permission for the font to be embedded in certain types of document files (e.g., a PDF) so that it will appear correctly when opened on another machine (only for viewing, not editing), but this wouldn't cover redistributing the original font files within your app.
Definitely clarify whether your usage is allowed with the foundry and/or with a lawyer before using it. If in doubt, better to go without it, unless you enjoy the prospect of being sued for a very large amount of money.
Using fonts in apps
Linear Mode
