Not familiar with the licensing agreement; I speculate you can buy a license and have all the access you want.
What trouble code are you looking for that Xentry is the answer for?
From the skimming I've done, typically Xentry work is beyond "reading trouble codes". Although much of what I've read about that people want to do doesn't appear to have safety implications, several are regulatory (not available on US code varient). I don't agree with several regulatory differences, but they should be respected.
It also appears several are features are software switches that enable features that could have been purchased. Flipping the switch without paying for the feature is also theft.