Both rovers have far outlived their expectations and are (and are recognized as) a tribute to the engineers who designed and assembled them.
Like the Viking landers before them, they were designed for a limited life, and like the Vikings, they smashed all expectations.
How long were they supposed to keep going?
IIRC, their original design lifespan was 90 days.
I’m just poking fun. They were to last maybe 2 to 3 months (IIRC), and have in fact far exceeded expectations.