3.0 licenses are no longer being sold and cannot be purchased. However, you can use a ROBOTC for VEX Robotics 4.0 license to activate ROBOTC for Cortex and PIC 3.0. To do so, install and open ROBOTC 3.0 (the download can be found here, latest version is 3.62: http://www.robotc.net/download/cortex/
) and navigate to the 'Help -> Manage Licenses -> Add License' menu option.
In the pop up window that appears, select the 'ROBOTC for VEX Robotics 4.x' menu option, then enter your ROBOTC 4.0 license ID and password. Click the 'Activate Online' button to activate the license and you should be good to go.
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