is 5` 1944 is that a good time for Knabes? is also in good conditions except that the soundboard has 2 cracks.
Also is it a good idea to clean the strings of the piano with metal polish?

Do not clean the strings.

About the strings... Please read this thread:

http://www.pianoworld.com/forum/ubbthreads.php/topics/1300073/1.html

1944 was not a wonderful time for piano manufacturing. The young guys in the factories had left to fight the war, the middle-aged guys were working in defense industries, and the old guys were getting very tired. Piano sales were down for a couple of reasons. Many raw materials were used for weaponry rather than for musical instruments, and families were not sure how things were going and were reluctant to spend money on new luxury goods. Things got much better in the new-piano world a few years later, with the post-war boom.

But never mind the general picture, do you have a grand or an upright (I assume a grand, because the strings must be visible to you for you to ask about cleaning them)? And did you have a tech inspect this particular piano before you bought it? Because the important question is not what was going on in the industry, it is whether you bought a piano in good condition.

Actually, the piano seems to be in good shape except of the old strings.[a piano tech has worked on the action]
the serial number is 131222 year 1944 but on the bottom of the keys says Style 50 Knabe keys feb.1942 Does Some one knows what does that means?
Also, some of the looks and parts seems to be Aeolians, but it has the logo of Knabe on the sounboard also has on the keys as Knabe 50 style 1942 and the logo Knabe Baltimore. The tech. seems to be a little confused about if it was made in the aolian factory or not.
he says it may be from Aeolian time, but the logos confuses him. Can some one help to understand?

In 1944 (or 1942) Knabes were manufactued in the Aeolian-American factory in East Rochester, New York. They used the old Knabe logos and emblems. The same goes for most of the other piano brand names Aeolian took over.