This trophy is story related and unmissable.
This will unlock after using the DeLorean to age the Cleanser bottle. Start out by taking the cleanser bottle from Emmett's Lab, then return to the DeLorean. Place the bottle in the DeLorean and take note that the light is green. Tell Doc, who will then test out the time machine, aging it 9 hours. Wait a moment until the light is green again, then tell Doc to try once more. Doc will fire up the time machine and when he returns, the Cleanser will be properly aged, and your trophy will unlock
Refer to the Trophy Walkthrough under "To The Expo!" , for more.