Five years. This guy sat through five years of WinZip nagging to get this screenshot. There's a reason companies don't really do shareware nowadays, and I think we've found it.
To be fair, old WinZip was never really shareware. Given that it never stopped working, it was more akin to really naggy donationware, with a stern warning instead of the customary sad, human plea. It goes without saying that new trial has a hard time limit, but by now it's been rendered more or less irrelevant by better, free-er alternatives, including Windows' built-in archiving software. WinZip plumbed the depths of human stinginess, and never found the bottom. Thanks for trying!
Anyway, five years is pretty impressive, but I'm willing to bet you guys can do better: who among you, cheapskate Gizmodians, has hobo-hitched the WinZip train the furthest? [Reddit]
UPDATE: Reader Ed G. wins by half a year. Keep sending! If there's a day one, Windows 98-having WinZip trial downloader out there, I want to find him.