Bill Cipher's "Hint"

In Sock Opera Bill destroyed the laptop instead of simply letting the countdown expire. Why? Well, as with the answers to many of these mysteries, the answer came several episodes later.

First of all, by destroying the laptop, Bill forced Dipper to look for any clues he could get from the laptop by simply looking at it. This helped to reveal the words "McGucket labs" on it in Society of the Blind Eye. If Bill had never destroyed the laptop, Dipper would never have found out about McGucket. Maybe Bill even used this as part of a master plan to destroy the blind eye society!

Second, McGucket obviously fixed up the laptop and, presumably, remembered his own password. This allowed the information in the laptop to be preserved, allowing McGucket to find out about the apocalypse early in Northwest Mansion Mystery.

So, in summary, by destroying the laptop, Bill actually preserved it. Thus he fulfilled his end of the deal with Dipper, as he both gave him a hint and helped save the laptop. It's even possible that Bipper's quest to find the journal was meant to help give Dipper another hint, a hint he will never get now because he and Mabel defeated Bipper.