There is sometimes confusion between an "update" and an "upgrade."
An update is sometimes referred to as a "patch" - it is often a fix for bugs in an existing release of software, and often contains enhancements as well. These updates are typically free. For example, during the life of Notation Software's version 3, there were free updates ranging from 3.0.1 all the way through 3.1.3 These were updates to the version 3 release, and they were free.
An upgrade is a new release of the software. Upgrades - being new releases - are for purchase. Our policy at Notation Software is to offer upgrade purchases at a discount to our existing customers. Our current release is version 4, and customers who purchased version 3 are eligible for a discounted purchase (upgrade) of the software with the discounted amount depending on the date of purchase. Those who received a free upgrade of version 3 from a previous purchase of version 2 are not eligible for a discount.
If you are a customer who wishes to purchase an upgrade, you can explore your options at www.notation.com/UpgradeOrder.php Just enter your registered email address and follow the instructions.