I am getting this rather bizarre issue where my game will randomly crash to desktop, with the Crash Log Analyzer reading "Max Memory Used - Try reducing memory usage by lowering setting."
I understand that Sims 3 is a 32-bit program, so can only use 4 GB of RAM (which works out to around 3.75 GB of usable RAM for gameplay after the game engine and core files take a bit). I have set the Sims3.ini file's line "Memory Usage Limit" to allow up to 6GB (I like to set things to allow higher than they can technically take so that I know it won't run out; I have the RAM).
The idea of this issue is rather simple: something happened that caused the game to need more than 4 GB of RAM, which it couldn't do because 32-bit, resulting in an immediate crash. The thing is, this shouldn't have happened. I used to play this game just fine on a laptop with only 4 GB of total RAM and with countless mods (my 250 GB hard drive, other than what space the operating system and the game itself took up, was completely FULL of mods). Sure, I had endless performance issues with the game trying to process all of that, but it never crashed due to simply running out of RAM. Since then, I have played the game with every expansion and stuff pack, tons of store content, and multiple hundreds of gigabytes (even up to a terabyte; though compressed and merged; I have my ways) on a newer rig with much more RAM and no out of memory crashes!

I now have 16 GB of RAM, allowing the game access to 6 GB of it (though it can only use 4), and only have a handful of mods (including the NRaas collection, the majority of the Fresh Prince collection; I like cars, and most of my Store content repackaged into mod .package files as I have always done; the game loads and runs faster when not having all those items "installed" via the Launcher, totaling out to 7.16GB in size across 9 .package files.

In all my years of playing (and modding the crap out of) the Sims 3, I have never ONCE witnessed one of these out of memory crashes. I have had 4 today. Is this some kind known bug in some setting somewhere (if not in the game itself, then most likely in NRaas) that caused this? It does not seem to be caused by a specific lot, animation, object, or other item, as these 4 have happened quite randomly (first while in CAS via Stylist trying to set up a career outfit, second while building a library in the high school I am working on, third while watching my Sim watch TV, and fourth while looking at a locker in said high school).

I know this is a long shot, as this game is so vast with so many variables that it is near impossible to pinpoint. I am just posting this in the hopes there is some kind of "obvious" first-shot solution to try that I am missing (like I said, never had these before in past years, so I really have no idea what to look for). If it is any help, I am on the Sao Paten map with Story Progression running regular immigrations (NOT Rapid Immigration) as the town is not populated by default.

Any help is MUCH appreciated.

[EDIT]
While initially researching the issue (after first crash), I read a few articles which mention an "LAA" (Large Adress Aware) protocol supposedly incorporated into the game which might allow to access 64 bit memory management? I don't comprehend this kind of language, so I haven't a clue what any of it means.
Does this make it possible to give the game usable access to not the 4 GB of RAM, or otherwise help solve my issue?

The ini file setting mentioned doesn't do what it sounds like it does. It's really a theoretical upper limit to the game's script heap, which is not the same as RAM usage, and by default EA has it set to 20 GB (not 2 GB). Increasing it to I guess 60 GB if this is what you have done would be neutral to the game at best, harmful at worst. Decreasing it to 6 GB would be detrimental. It's unfortunately too easy to miscount the 0s or assume the wrong unit of measure as many have done when reporting that changing this value actually conveys some benefit. Leaving it alone at 20 GB is the best idea. There is nothing anyone can or should do directly to change the amount of RAM the game calls for and uses; affecting that metric indirectly by relieving stress on the game of course is always a good idea.

LAA doesn't mean 64-bit memory management. It means that as of Patch 1.17 when this got implemented, TS3 will actually address ~3.7 GB before it loses its mind with upwards of 3.5 GB being the danger zone for most of us. Before then the limit on Windows was indeed 2 GB. On the Mac version of the game, currently it is still 2 GB.

@nitromon: setting the ini file back won't solve the problem, as I first increased it because of the crash (it crashes once before increasing it). Seeing as it provided no improvement, I will still set it back to default to prevent other possible issues.
Also, what kind of mods tend to cause memory leaks? Aside from NRaas and Fresh Prince's cars (which I've never had issues out of), all of my mods are buildings items (doors, windows, roofs, floors, and walls) with the exception of two mods to convert some CAS items to other age groups and genders. I am, of course, also using map mods (currently on Sao Paten. I was using a map called Greymont Bay, but switched pretty quickly due to routing issues slowing the game down to unplayability.

@igazor: 20 GB is high. In that case, I did indeed set mine to 60. That's probably not too good. I will change it back.

While doing some more research on common memory leak causes, one possible solution I found was to lower reflection settings. This would make sense as every crash took place on a lot or around a mirror (CAS and Stylist both have mirrors, the house has six mirrors, and the school is utterly covered in mirrors with full wall-to-wall floor-to-ceiling mirrors in EACH bathroom). I am going to try lowing it first and see if it crashes again today.

I turned off reflections, and haven't had a crash since. I have even left my game going over-night and just woke up to see it STILL running!

I am going to try to raise the reflections back up because I really don't like how water looks without any reflection, but I will just set it "mirrors and water" rather than "mirrors and super water" or whatever the highest is called. I wish there was a way to enable reflections for mirrors and water separately.