Royalty
late Middle English: from Old French roialte, from roial (see royal). The sense ‘royal right (especially over minerals’) (late 15th century) developed into the sense ‘payment made by a mineral producer to the site owner’ (mid 19th century), which was then transferred to payments for the use of patents and published materials.
wiktionary
From Middle English royaltee, roialtee, royalte, from Old French roialté, roiauté, realté (compare earlier Old French realted(“realm, kingdom”)), from Vulgar Latin *rēgālitās, from Latin rēgālis, equivalent to royal + -ty.
etymonline
royalty (n.)
c. 1400, "office or position of a sovereign, royal power or authority," also "magnificence," from or modeled on Old French roialte (12c., Modern French royauté), from Vulgar Latin *regalitatem (nominative *regalitas), from Latin regalis "royal, kingly; of or belonging to a king, worthy of a king" (see royal (adj.)).
The meaning "royal persons collectively" is from late 15c. From the notion of prerogatives of a sovereign the sense expanded to "prerogatives or rights granted by a sovereign to an individual or corporation" (late 15c.). From that evolved more general senses, such as "payment to a landowner for use of a mine" (1839), and ultimately "payment to an author, composer, etc." for sale or use of his or her work (1857). Compare realty.
