Are you a purchaser or a reseller?
Has someone asked you to buy them a copy of ABCpdf?
If so, then unless your client has asked you to purchase a Standard License, they do not want this type. They want a Professional License.
Standard Licenses are more economical but feature limited. This means that if your client is not expecting certain features to be missing, then they will be unhappy when they discover that they are absent.
This may occur sooner, in which case things can generally be rectified; or later, in which case you will typically need to purchase a new license.
If you are not sure what type to purchase, please get a Professional License.
You require one license for each installed copy of the software.