Unlike Microsoft, Apple seems to understand that sometimes it's okay to not milk every last cent out of every last possible channel — looking at you, ads in the operating system. I would wager the revenue they could make on making that software a recurring subscription is pennies compared to the marketing ethos that every pro artist uses Apple, and so should you. The amount of hardware and iCloud subscriptions they sell to all aspiring artists, kids who want to be like their heroes, their parents, etc, should far outweigh what they could make from the other end.