Regardless of if you use the original font files, or convert the font to outlines; if you're using a commercial font for commercial use (even sometimes personal) you 'generally' need to have purchased a licence.

If the Type Foundry get wind that someone has used their font, say in a poster campaign, or any other kind of commercial sense, and they dig around and discover this was not purchased by said client, then client could be liable.

If you are a client, and your designer uses a commercial font in your design, then one or both of you need to have purchased the licence in order to use it, regardless of if the font is outlined or not.

I typically will purchase a commercial font, from Myfonts, and designate the client as the Licence Holder, as after all, it's them who will be using it commercially. If I use that font again for another client in a logo design, then I'll ask them to also purchase a licence for that font.

Just because a designer might have purchased a font, this doesn't give the client carte blanche to then use it commercially even if font is converted to paths/outlines.

Who ever buys a font generally holds the licence to use it, so this is where some designers/clients get confused or in trouble.

There are always exceptions in the Licence, so as others' have said, always check the Licence first, but generally assume you need to have purchased a licence for the 'right' to use that font in whatever way it's being used.