Are they worth it(Last long)?

100%. I've been using various mechanical keyboards for ~15 years now. One of my first mech keyboards was a CODE - I sold it six years ago to my mate and he reports that it's still been going great, no issues at all. My current main keyboards are a Drop CTRL and a Keychron K14, both of which have been going great as well.

In fact, I'd argue that on an average, mech keyboards last much much longer due to:

• High-quality switches which are rated for several million keypresses (100 million for MX Browns)
• High-quality plastic keycaps (double-shot PBT) which aren't susceptible to shine and legend-wear, unlike the cheap (ABS) keycaps you'd find on regular keyboards
• Swappable keycaps means you'd never get bored of the same look + easy to source replacements if you need them
• Swappable switches means you can replace a switch (if on the rare occasion it fails) - or you can completely upgrade your typing experience by choosing different switches with more suitable resistance/comfort/speed/tactility/sound etc.
• Standard removable USB-C cable means you can replace the cable in case it gets worn out (unlike most cheap keyboards which have fixed cables). This also allows you to use high-quality braided cables which last much longer.
• Overall modular nature of these keyboards: practically every part is replaceable/customizable/serviceable - even the firmware

Honestly, there's no comparison at all between a proper mech keyboard and a branded OEM keyboard from the likes of Apple/Logitech/Microsoft etc - you're just paying for the brand name to get an average quality keyboard with way less repairability/modularity/customisability.