Could embedding a font with the use of PHP be regarded as read-only?
What do you mean be "PHP embedding"? Creating images on the fly? PDFs?
Where? On a webserver?
Only one way I know: PHP + gd (library) with enabled freetype and t1lib.
The result is pixel image.
Most font vendors wouldn't consider Web server based rendering “embedding” as such, but it doesn’t fit into the normal/traditional EULA model either - where you're counting users and maybe output devices. For this reason Ascender and others do licenses fonts under a per-Web-server license.
PHP embedding is a bad term. I mean creating an image with text in it dynamically using PHP. To do so you need to have the font files on your web server. Could a skilled programmer find the files and download them?
You need to check the EULA for "server use" not "embedding". As Sii already said this sort of use usually requires an additional server license.
>Could a skilled programmer find the files and download them?
If the server is pwned by a hacker - so are the fonts. But unless these are super secret proprietary fonts, that's likely to be inconsequential. There are easier ways to steal fonts.
Why not use sIFR instead?
In that case, I'd need to purchase an extra license. I might just have to anyway, cause PHP seems to mess up anti alias for dark coloured text.