There are factors that can damage electronic circuits over long periods of time, such as electromigration.
But there is no specific wear mechanism in RAM as there is with Flash or mechanical storage.
There are a number of things that can possibly look like wear, all based on defects.
RAM does not slow down over time.
How long will ram last?
Ram should last forever and a day or put another way it should outlast you. That said due to manufacturing defects you can get early life failures but you have already had the ram two and a half years so that should not be a problem, so the ram is now probably the most reliable part of your computer.
How do I know if my RAM is bad?
Random Access Memory (RAM) wears out over time. If your PC frequently freezes, reboots, or brings up a BSOD (Blue Screen Of Death), bad RAM just might be the problem. Corrupt files can be another sign of bad RAM, especially when the corruption is found in files that you’ve used recently.
How often do you need to replace RAM?
Honorable. You should only upgrade RAM when you want to. As RAM gets faster and higher capacity RAM gets cheaper, I would say replace your RAM when you get a motherboard that won’t support DDR3 for any longer, or about 5 years.
What causes RAM to go bad?
Electrostatic discharge can damage your computer. Excessive heat can cause RAM and other parts to wear out over time. Individual components can overheat, or heat from one component can cause damage to adjacent parts. This is the most likely cause behind a damaged RAM.