Manual – description of the menu prompts and options

select object to trim by clicking at the part you want to save / select object to split – like the prompt says, here the user should indicate what object is to be trimmed or split. Keep in mind, that when clicking on an object that is warped (e.g. closed polysurface), you can find the object twice or even more times in the pop-up list; it allows you to choose point that is closer to you or further (in Trim command it has influence on which part will be kept and which will be discarded).

DeleteLast – deletes the last picked cutting curve

Extend – extends the free ends of cutting curves to the borders of the surfaces on which they lie

Options

GroupIntersectionCrvs – Combines cutting curves which originate from the same object, or treat them separately. It also works on free curves whose ends are located at the same point

IncludeCrvsAndEdgs – Includes free document curves and surface edges of the cut object as cutting curves, or disables this function

DumpCurves – Turns cutting curves into free document curves and terminates the whole command

Register -> GenerateComputerID – Generates a character string that is needed to purchase a license and obtain a key file by the user

Register -> ConnectWithKey – Allows the user to indicate location of the key file after purchasing the plugin and receiving the key file by email

or watch this video tutorial

..it is a bit outdated but still explains the most important things 😉