Magical Life Extension is the use of magic to halt, or even reverse, aging. It also encompasses the use of psychic magic to obtain control over the processes of memory retention. It was heavily restricted during the Golden Age, but has been historically common among magic users from the Pre-classical Period to the present. Magical life-extension has its limits in terms of the achievable duration; it is difficult to apply to persons other than the caster. Still, the obvious allure has resulted in many a deal between a rich pony and an unscrupulous mage willing to try her horn at it, to variable results.
Magical Life Extension, if begun early, also extends the reproductive window. See e.g. Eldritch Lore who became pregnant with her first child in her second century of life.
There are various known complications of repeated magical life extension. Due to the accumulation of disabling complications (or, occasionally, simply due to ennui), most practitioners choose not to extend their life beyond two centuries. Bluestar the Brilliant, however, is reported to have lived over eight hundred years before succumbing to an unexpected, fatal complication in 2835 AE.
True Alicorns such as the legendary Princesses were supposed to have been immortal, although the nature of this everlasting life is subject to speculation. Pegacorns and other bitypical ponies are not immortal.
The Undead and spirits are also thought to be immortal. Fortunately, little of them is known on the Isle of Yore.
Life-extension through alchemy is so common throughout zebra lands it is considered little more than a supplement for zebra of advanced age, to be taken alongside things like Calcium and Vitamin D. Following their childbearing years (for any kind of permanent self-augmentation is frowned upon prior to that for obvious reasons) zebra typically begin taking a prescription from their local alchemist that grants them with some of the longevity of various flora, fauna or other types of worldly materials.
Similar unicorn MLE, this does not come without risks. Particularly should the alchemy be poorly done, if the wrong combination of elixirs are taken, or even if the same elixir is taken too frequently. As an example, if one repeatedly took a potion that gave them more of the eternal qualities of stone, they might start to become heavier and stiffer. If they repeatedly took on aspects of the trees, their skin could grow more and more rough like bark and the blood in their veins wouldn't flow as well.
As a result of this practice, the lifespan of zebra tends to be well in excess of that of the typical pony if they receive their elixirs regularly. They also tend to look particularly odd-looking toward the end of their lives due to the inevitable accumulation of minor mutations this practice entails.