Excuse me that I did not reply earlier, I just could not.
Following the instruction by Damien3, I deleted the two files.
The truth is that, I could delete the “com.audirvana.Audirvana-Plus”, but not the “com.audirvana.Audirvana”, because the latter was not found.
As Damien3 said, the license key was required on the next start, but it did not start anyway.
It simply returned to display the same message:
“Unable to check your license Please check your Internet connection, and try again”.
I started to think of a possibility that, maybe by renewing my license for the version 3.5, it became invalid for the version 3?
I received the offer in February 2020 that I could renew my license for the version 3.5 for free, but I had to do it soon, or it will not be free.
So, I did renew my license, but I never installed the version 3.5, and I kept using the version 3.2.20 on Mac OS 10.9.5.
I do not remember any notice that renewing the license for the version 3.5 would revoke my license for the version3, and in fact, I could use the version 3 until December 2020.
Anyway, that was it with the Audirvana Plus 3.
Time passed by and I bought a new M1 Mac mini in February 2021, and I installed the new Audirvana 3.5.44 to it.
Thankfully, I could start it without problem with the same license key.
I am quite surprised that the new version 3.5 sounds very well although it does not work at “direct mode”.
Comparing with my memory, the version 3.5 sounds richer and denser than the version 3, as if the amplifier has got more power.
I can not say definitely which is better, but the new 3.5 is not bad at all, and I feel quite relieved.
I wish I could compare listening back and forth with the old version 3, but I do not miss the “direct mode” as much as I had imagined, because the new 3.5 sounds so nicely.
It could be that the old version 3 was better when I want to listen to the music for hours continuously, but if I want to enjoy the music for 30 minutes, the sound from the new version 3.5 is more satisfying.
By the way, there still lies a question.
One license can run the Audirvana on two PCs, as I understand.
I wonder what happened to the license I used for the version 3 on my old MacBook Pro.
I never had the chance to invalidate it, so am I using the new Mac mini as my secend PC for the same license?
I will find it out when I have another PC, but maybe, new version 4 can come out before that, and I am quite sure that I will up-grade my license for the new version.
I hope it would renew my license situation.