Saru,
You have two options: developer-based licensing and domain-based licensing. You can choose either.
For domain-based licensing, you can choose Company License (if a number of servers is <=5) or Site License (if more then 5 servers in a web farm). In case of domain-based license you get only ONE MONTH of upgrades/support.
In case of domain-based licensing your are not limited by a number of developers.
For developer-based licensing you can choose Singe Developer License. Developer-based licenses provide ONE YEAR of upgrades and support period. In case of developer-based licensing, you are not limited by a number of production domains/servers. So you can use the control in any number of projects.
Prices:
Company License: $149.90
Site License: $199.90
Single Developer License: $199.90
(more prices: http://www.9rays.net/order.aspx?productFamily=TreeView_ASP.NET_2 )
From my personal perspective, Single Developer License is more valuable for you, because it will not limit you on deployment of your projects and additionally provide a year of upgrades/support (not a month as domain-based licenses do).
When deploying your application, you do not install license keys. Retail control DLL will have property description on license that you own.