Why I forget

Know why I forget things?
I know why

Coz each time I forget 

I'm sure, it is either necessary or optional

If it is necessary I forget it all of a sudden

And the thought pops up after sometime

If it's optional it is not very easy to forget it completely

Even if I forget it, It hints every now and then

This is how I forget things

Know why I remember things?

I know why

Coz each time I remember 

I'm sure, it is either inevitable or unpleasant

If it is inevitable, I need not do anything

If it is unpleasant, I remember to forget it always

This is how I remember things