Howdy! It's not possible to switch premium themes between blogs, however, since you're within the 30-day refund limit, you can initiate a refund for the the theme on the hurricanelil blog, and re-purchase the theme on the kentuckymoonherbals blog.
To initiate a refund for Gridspace, head to the Dashboard -> Store -> My Upgrades. You'll see a button to cancel your purchase.
If you have further questions, please post them over in the Premium Themes forums and one of our premium themes gurus would be happy to help you. :)