How long can slin stay unrefridgerated

Can anyone give me an exact time that slin can remain out of the fridge? I have heard its 28 days and then the slin is no longer viable, but I'm not sure if that meant it can stay out then be refridgerated and still be ok, or it would just have gone bad. Any input would be appreciated

This is regarding Humalog if it makes a difference.

As of now, refridgerating is out of the question, so my options are hiding it in a cooler in my closet with an ice pack (and rotating icepacks) or just leaving it in a dark place thats not too hot.

I know it can stay out for alittle while so I was thinking about doing the first option and just preloading a weeks worth or so, but am also concerned that it might freeze, in which case I know its not good any more.