You shouldn't have to install the render engine unless you're planning to run a sort of render farm.
To use After Effects in Render Engine mode, a separate install has not been required since... gosh, After Effects 7.0? Possibly CS3; my memory gets a bit hazy that far back.
Render Engine is now included with the main install of After Effects. Note that in order to set up multi-machine rendering there are some new steps you need to take for licensing, see this article for more information:
ah cool - just curious coz when i updated about a month ago i was prompted to install the render engine - which i did but it didnt make any difference anyway:)
No problem! but Im still curious why i was prompted by CC if i wanted to install the render engine only about a month or so ago - i did install it along with AE - but it didnt make any difference:)
The latest update of AE didnt prompt me and i uninstalled the RE - apart from some folder permission setting - all is good now:)