Licensing question

[Mahesh T. Pai]

Clayton Dukes said on Thu, Feb 25, 2010 at 10:07:48PM -0500,:

 > 1. I want to allow smaller companies, say less than 50 employees, use
 > my software free of charge.
 > 2. Larger companies will pay a licensing fee (based on the size of the company).

Not free. You cannot discriminate between users. 

 > 3. Any modifications/bug fixes should be shared back.

Not free again. 

 > 4. Users cannot use my code in a commercial product without my
 > permission.

Not free. You cannot restrict users from using your software the way
they like.

 > Can you recommend a license that fits this ideology?

You need a lawyer. 

 > Also note (not sure if it's important?)
 > My software is written using other open source programs, such as PHP -
 > does this affect my license?


Depends on the specific license and how your software works. As said,
you a lawyer.

-- 
Mahesh T. Pai   ||  http://[paivakil|fizzard].blogspot.com
End Users are just friends who haven't submitted a patch yet.