Follow the step-by-step instructions here to move the same version PreRoll Post from one computer to another:

• Run the full installer on the new computer, and update on the old computer if needed.
• Close the application on both computers. Then copy the contents from the ROOT of the old computer:
• ~Library/Application Support/ImagineProducts/PrerollPost/
• Put that into the same location on the new one computer.
• When you launch PreRoll Post on the new computer it will connect the database.