Bug-fix updates are free, as are minor version (.x) updates. Major version (x.) updates are on a case-by-case basis; thus far, in 4+ years of selling Chinese dictionaries we've never charged for a software update, and we're hoping that we won't have to do so in the future either, but there likely will be new features in future updates that do have an extra fee associated with them - for example, stroke order diagrams and (some) audio pronunciation. This will likely work much like the Hanwang recognizer upgrade did for PlecoDict - free for new users, small upgrade fee for previous-version users but the rest of the software will work OK even without the upgrade.