When you buy Studio One v4, you get all updates for v4 for free. For instance, all v4 updates including the latest v4.6.2 update have been free. There are no extra charges for v4. When v5 is released, you will get a special discount offer from Presonus to upgrade. You will then get all v5 updates for free. Basically, all major updates that change the primary version numbers are paid updates and all minor revisions that do not change the primary version number are free.