Minor updates and maintenance releases of the commercial versions of NoteTab are free for users of the corresponding major version. In other words, if you purchased NoteTab v4.00, all updates up to v4.99 inclusive are available for free. Major upgrades (version 5.*, 6.*, etc.) are available to registered users of previous versions at a 50% discount. However, the upgrade is free for those who purchased the corresponding version of NoteTab 120 days prior to the release of a major upgrade.