Any individual or device (and I think sofware, as in your case) that is going to access Oracle software is counted as a named user (or named user plus), so I think you should not create more virtual users than the numer of named users the license allows.
Here is the description of a named user plus (and I think there is no difference in this part compared to a named user):
“<b>Named User Plus: is defined as an individual authorised by you to use the programs which are installed on a single server or multiple servers, regardless of whether the individual is actively using the programs at any given time. A non human operated device will be counted as a named user plus in addition to all individuals authorised to use the programs, if such devices can access the programs. If multiplexing hardware or software (e.g., a TP monitor or a web server product) is used, this number must be measured at the multiplexing front end. Automated batching of data from computer to computer is permitted. You are responsible for ensuring that the named user plus per processor minimums are maintained for the programs contained in the user minimum table in the licensing rules section; the minimums table provides for the minimum number of named users plus required and all actual users must be licensed…..</b>”
I think you should confirm your situation with an Oracle sales rep.