If olam (and its Greek equivalent aionios in the LXX) has a figurative sense whenever it refers to things of limited, temporal duration then it would seem that it is used in a figurative sense in the OT a good deal more than it is used in a literal sense! But perhaps itās not being used figuratively at all; perhaps olam is simply a very elastic word that embraces the whole duration of whatever subject to which it is applied. Or even more radically, perhaps olam never literally means āforeverā at all, and was not used by the inspired writers to express the idea of eternality, or of Godās eternal existence.
My undestanding is that olam is not an argument for or against the eternality of that which is thought to be eternal in the absolute sense of the word (such as God). While Godās existence was understood to have no beginning and no end, it is not this fact that the inspired writers were emphasizing when they used olam in reference to him. Rather, I believe it is Godās continuous, faithful and personal involvement with humanity in all of the generations and ages of this temporal world (whether past, present or future) that is being expressed and emphasized by their use of the word olam. Godās existence and activity beyond the duration of human existence on this earth is not, I donāt think, in view when olam is used.
Imagine if they did that in Matt 25:46 with aionios life & aionios punishment! 
Such humor, it made me laugh.