Khmer Unicode and Font are two differents things.

Khmer Unicode and Khmer Unicode Font are two different things. Please... Please... understand.

• Unicode is a Hexadecimal value, represent character. Example Character ក = Hex1780


• Font is the Graphical representation of character. It contain a table that map Unicode value to graphical character.

There is an international organization (www.unicode.org), the mother of Unicode. This org manage and authorize what Hex value represent what character in what language. It is called Unicode. No body else can create new Unicode without this organization 's approval.
So, do we need to pay license fee to Unicode.org to use this unicode?
NO, we don't. Every body can use it as long as they don't change Hex 1780 to ខ or some thing else beside ក.

Like wise, Khmer Unicode is not belong to any Companies or Organizations, but font is.

Khmer Unicode table
PAN Cambodia Fonts
KhmerOS Fonts