Can i upgrade from window 7 home premium to professional ?

YES and NO .
You CAN NOT upgarde windows using normal licence key . Windows will not accept it!
(It is crap to be honest,because microsoft should take account,that somebody has normal licence key which prefer to use).
For example.
I bought new laptop without  microsoft windows tax, because i had licence to use already.
However, company where i bought laptop installed test version of Windows 7 home premium, so i tried to upgraded windows from home premium to professional,but i couldn't,because i have normal licence key,so i  needed to install windows 7 pro from beginning .
Crap. is it?I think MS should consider expand upgrade to allow to use normal licence key too.

 So ...

You CAN uprgrade using upgrade licence key only!
 On microsoft page you can find possible paths of upgrade

Link to page with nice table that shows possible paths:
http://technet.microsoft.com/en-us/library/dd772579(WS.10).aspx

Here is little summary:

1)From Windows Vista (SP1, SP2) Upgrade to Windows 7

• Business  >Professional, Enterprise, Ultimate
• Enterprise  >Enterprise
• Home Basic > Home Basic, Home Premium, Ultimate
• Home Premium > Home Premium, Ultimate
• Ultimate  > Ultimate 

2)From Windows 7 Repair-In-Place Upgrade to Windows 7

• Enterprise  > Enterprise
• Home Basic  > Home Basic
• Home Premium > Home Premium
• Professional  > Professional
• Starter (x86 only)  > Starter (x86) 
• Ultimate  > Ultimate

3) From Windows 7 Anytime Upgrade to Windows 7

• Home Basic > Home Premium, Professional, Ultimate
• Home Premium > Professional, Ultimate
• Professional  > Ultimate
• Starter  > Home Premium, Professional, Ultimate