You’ll have to do way more in the way of details.
What does, “does not work” mean? Do you get an error? What operating system are you attempting to install on? Was this an upgrade purchase?
Important to note: PM 7 is more than 15 years old and has no support under modern operating systems on either Mac or Windows. Attempting to install it on anything newer than Windows XP is not likely to work at all.
i am operating windows 10. After i enter the serial number a window pops up that states that the serial number is incorrect.. so i guess i should not expect it to work anyway?
Two ideas that MAY work to install and/or run old programs in Windows 10
-RIGHT click the program icon or EXE and select a compatibility mode in the pop up option window
-or Run as Administrator http://forums.adobe.com/thread/969395 to assign FULL Windows permissions may help... says Encore, but sometimes required for ALL Adobe programs (this is NOT the same as using an Administrator account)
-or more on permissions https://forums.adobe.com/thread/2293598
-and more help in http://helpx.adobe.com/creative-suite/kb/invalid-serial-number-cs4.html