Are you a first-time user of RockSim: Order it at: www.apogeerockets.com/Rocket-Software/RockSim/RockSim-v10-Single-User Version 9 users: You get a FREE Upgrade for being so patient and staying loyal to Apogee Components. And v9 doesn't even need to be running or activated to get the free upgrade! The link for the free upgrade is: https://www.apogeerockets.com/RockSim-v10-Free-Upgrade Did you have version 8, or older and want a low cost-upgrade? Note: You DON'T even need those old versions to be operating. We'll guide you through the upgrade process and give you a FULL edition of v10. To upgrade from v8 or older, go to: www.apogeerockets.com/Rocket_Software/RockSim_Upgrades Installing RockSim video for Windows is: https://youtu.be/87aOCdox8es