What item have you been using on a daily basis for the longest amount of time?
Sometimes I will use something and realize I've owned it forever. It's a nice change in our throwaway reality. I think my personal record is a bicycle multi-tool I got for one of my first bikes, ~25 years ago. Still have it, still use it. When it comes to electronic devices I have a Panasonic mini Hi-Fi from ~2005. Never felt like changing it.
Sennheiser headphones that I bought for about $20 about 10 years ago. The cable is indestructible. I once had to resolder it to the speakers because it my cat pulled it out, but the cable itself has endured all kinds of abuse without breaking. And the sound is fantastic.