I am leaving my cats for 30 days while I'm out of town. Will they remember me when I come home?

I am slightly obsessed with my kitties- we are VERY, VERY close and affectionate. I wonder what they will think being dropped off at a stranger’s house for the first time. Will they, and are they capable of, wondering where I am? At some point will they forget all about me?? What will go through their cute little minds? And, how will they act after 30 days when I come home?! We have never been apart this long….And, yes, I know I must sound slightly insane, but, I really do have the coolest and cutest kitties ever!! ;)