My u-lock was giving me some trouble over the past few weeks, and I wasn’t sure why. Then I realized that I had been using it almost every day for a year and a half. I had a couple backup keys that came with it, so I started using a new one and the lock worked like brand new! The old one is on the bottom. You can see that some of the notches are almost completely worn away.
If you have a Kryptonite lock, be sure to always one or two extra hidden somewhere safe. It also helps if you squirt some Triflow (or other light weight oil) into the lock every few months, especially during prolonged periods of wet weather. If water gets into your lock, it may freeze in there. You can solve this problem by thawing it with a lighter, or prevent it by using the lock’s shield and hanging it keyhole down. With a little preparedness and preventative maintenance, a Kryptonite lock can last for years.