How to get my pre-approved labor checked

[milwius]

Hi,
One company is willing to provide me a pre-approved labor provided I join them and they sent me the labor so i can get it checked if I want to.

Can you please tell me how to I get this checked to see if it is a valid labor or not?

How do I check if the labor suits me or not.

How do I know if the labor has been used for someone else earlier than me or not?

This is kind of urgent for me and any immediate help is appreciated.

Thanks,
m***ius