Font Licensing
A font licence is the agreement that permits a company to use a typeface. It regulates separately whether the font may be installed on workstations, embedded as a webfont, bundled into an app or embedded in a PDF, and usually caps usage by number of devices or page views.
In practice
Fonts are bought like software: you acquire a right of use, not the typeface itself. The most common mistake is carrying a desktop licence from the design software over to the website; that nearly always requires a separate webfont licence. Before buying, check that the licence covers your actual volume and whether self-hosting is permitted, which is usually the cleaner option in data protection terms than loading from a third-party server. Keep invoices and licence texts, because foundries monitor websites systematically and any shortfall arrives as an invoice, not a request. Freely licensed typefaces are a serious option when you have read the specific licence.