This may not qualify as “buy it for life” strictly speaking, but I was able to fetch docs, drivers and firmware from the trendnet website for a wi-fi USB stick made in 2005. Their website is also openly accessible with no Tor blocks or shitty shenanigans like forcing you to give them info. I could simply download what I needed without digging around archive.org. I’m somewhat amazed by this.

They discontinued it and have a successor model, but the fact that they did not erase the old product from history (unlike just about every other corporate supplier) is noteworthy particularly when they tend to make low budget hardware.