Do I need to buy a license? For commercial/business use yes, you need a license to use RGraph. RGraph is not free software.
For non-commercial use (eg personal, charity and educational), RGraph is freely usable though. You can read the license itself
here.
How much is a license? A license is a one-time fee of £49 (UK pounds). That's roughly $81 (US dollars) at
todays (8th September 2009) exchange rate.
Where can I read the license? The license is further down this page.
What does the license cover? The RGraph license covers RGraph as a whole. All code that you find in the RGraph archive is covered by the RGraph license.
Can you send me an invoice? Of course, simply go here: http://www.rgraph.net/invoice.html, enter your email
address and you'll be sent an invoice that you can use for tax purposes.