What are the legalities regarding using licensed fonts for webpages? It will be used for a for a commercial site. I do not want to get into trouble by using it without a license, (although I do hear a lot of complaints about the industry in general), but how severe are the penalties realistically?
There's no universal answer to this. You're also not really saying what you mean by "using" the fonts, though I'm going to guess you mean embedding. Even if not, the answer is pretty much the same:
You need to look at the license you agreed to, from the foundry that produced the font. Some of them have relatively liberal usage clauses dis/allowing use in certain media, some disallow embedding altogether, and some allow it as a sort of add-on to the base license.