can we do something like if it's not accessed for x amount of time delete it? #290

I have two concerns about this package.

1. I am not sure how much memory it will be using, I am creating cache in my solution per user. what if my users increment from let's say 100 to 1000. can you suggest me something to do a test for memory usage?

2. can we do the time thing if it's not accessed for x amount delete that key and value?