You will need to purchase the upgrade first.
When you buy your license upgrade through our online webstore, you'll need to be logged into my.presonus.com. You'll be asked to choose which license you want to upgrade. A drop down will appear where you can choose which of your registered versions of Studio One you are trying to upgrade.
If you bought this in a retail store and you have a receipt with a key on it, you would log into your my.presonus.com account, go to your Studio One 3 key that want to upgrade and click the Green Upgrade Button under your license key.
If you're still having trouble contact our sales team for assistance in the USA or abroad contact the PreSonus distributor for your country.