After Canva’s acquisition of Affinity design software sparked concern regarding the future of its one-time purchase pricing model, both companies are now promising that users won’t be forced into subscribing to the service — ever. On Wednesday, Canva and Affinity published a joint pledge promising to keep Affinity software “fair, transparent, and affordable,” including “the perpetual licenses that have made Affinity special.”Affinity’s design software suite is considered to be one of the few via...