A Mobile App license grants the licensee the right to distribute the copyrighted letterforms to a user base. It’s hard to know if that user base is tiny, or massive, and in fact the YouWorkForThem Mobile App license allows for up to 500,000 unique users per calendar year. More than 500,000 users requires a custom extension, which we are happy to negotiate for you.
From the foundries‘ point of view, they routinely see iOS apps making many, many times the sum of a font license, or more, and want fair compensation for contributing such a major asset to the product design, thus the common 10x multiple.