license keys?

hello well i am trying to work in one of my clients premium wordpress themes and as i installed in my pc then it is asking for license keys?
is it possible to install without keys?

Not if its asking you for a key when you install it.

and is there any alternative way to work on those premium themes?

Purchase it.

rachel i didnt get u

I think Rachel’s answer was quite clear. You are dealing with a premium theme with a licensing key. You should probably ask your client where the theme was purchased, and then ask those folks your questions regarding how to best use or circumvent their licensing policies.