Why isn't "long-run aggregate demand (or LRAD)" a thing? To give you a sense of where I am in my understanding of economics, I've just learned about long-run aggregate supply in the neoclassical/monetarist view as a vertical curve. It occurred to me why doesn't the same thing that happens to SRAS happen to aggregate demand over the long run - I'm envisioning that prices adjust in the long-run such that prices have no effect on anything; whether supply, demand, or anything else to do with purchasing habits. By the same reasoning as for aggregate supply, it seems like aggregate demand in the long run is also a graphically a vertical line. In the long run, where wages can adjust to match prices, people will continue buying the same quantity demanded as before just with a higher price level, right? 

But I'm assuming, from what I've seen, that we don't differentiate between aggregate demand in the long and short run. What knowledge am I missing? 

I'm in SL IB economics and we've just reached macro. I also have a shallow understanding of the Keynesian AS curve.
The main reason why long run aggregate supply is vertical is that in the end the production capacity of every country is limited. In the end there is always some maximum number of number of stuff we can produce (of course, there can be economic growth which expands our production possibilities but the LRAS is basically given by the production possibility frontier that will at every point in time be finite).

However, there is no such restriction on people’s demand. One of the basic assumptions of economics is non-satiation. More is always better than less. However, another basic principle in economics is that marginal utility of consumption is increasing but at a decreasing rate. That is more is always better but the more you have of something the less valuable the thing to you becomes. This is what makes demand decreasing function of price. The thing is that this holds both in short and long term. It’s not like people are only non-satiated in short run, and also it’s not like the marginal utility of consumption increases at decreasing rate only in short run.

Vertical demand curve would basically imply that consumers would never want to buy more of the aggregate product which is certainly not true.

So to sum up, LRAS is vertical because of physical limitation on our production. At some point no matter what’s the price it is not possible to produce more. For example, a writer can only write so much hours in a day so even if someone would offered the writer million euros per hour he or she can never work more than 24h per day (and considering that would kill the person probably I should say not more than max 18h) so the supply will be at some point completely vertical given by the production possibility of the economy. However, no such restriction exists on people’s demand. People’s needs are endless and people will always prefer more to less if the price drops sufficiently (since utility is not increasing at constant but at decreasing rate).