Our parsley plants just die off after so long. The leaves start turning a beige-white and then the plant just croaks. It's happened time and time again. Doesn't matter if they are in the ground or in a pot. Don't know if it's that the heat finally just gets to them or they just have a "shelf-life." I've never timed it to see how long they last but it's always been well over a year, probably closer to 2.
Unfortunately, sage doesn't make it thru the summer here either, no matter how much water it gets.
Our rosemary, however, is going strong. I keep having to cut it back so it doesn't completely block the sidewalk or the entryway at the front door. It's probably 3' in greatest diameter and 2-1/2 feet tall at its highest.
Basil just gets too woody after a while here even if it gets enough water. We have regular and Thai basil growing. The Thai basil plant just keeps re-seeding itself. With a little precursor to the start of our rainy season a couple of weeks ago, we've had a couple of new Thai basil plants pop up and they are growing strong. It's like the Energizer Bunny, just keeps going and going, think it's been 4 years now since we first started growing it. Once I can see the plant is starting to go, I'll quit pinching off the little blooms and let them flower and re-seed themselves, and then pull the old plant out to make way for the new ones. The regular will re-seed itself too, though no where near as aggressively as the Thai seems to.
Thyme usually doesn't make it thru the summer heat either, just can't handle it.
Oregano has to be potted here. Learned that the hard way. Even in the pot, it will still put out roots and start growing in the ground. I sat the pot on a large flat stone this last time.