R does not utilizes/consumes/responsible for memory Management. 

R gives everything to system to perform the Memory Management. 

To check the Memory-limits in R.
Command: help(“Memory-limits”)
Command: memory.limit()


Command: memory.limit(36754)

To find the size of an Object 'x'
Command: Object.size(x)

To find the size of all the objects created.
Command: Object.size(ls())

You can free up the space allocated to a variable by using 

Command: rm (x) x- variable

All this activity is in respect to byte storage and memory limit and how you can use it effectively with the system.