A quick update on this issue. Apparently, it is annoying and finally got resolved. This what I learn throughout this process. So my 3 months free subscription was coming to an end, and despite I purchased an additional year of SIRUS subscription to start on the last day of the free subscription, I still got all these nonsense of trial end notification and SIRUS preview channel and I had to agree to the terms before to listen to any channel in addition to "check SIRUS antenna"....etc. I tried the work around mentioned here to program the diamond button at the Steering wheel and didn't work! Also, I took it to the dealer to find out why all these issues and the dealer had no clue other than this work around diamond thing. They were not able to do anything and the issue persisted even after they "updated the radio at PCM". Therefore, I called SIRUS technical support and spend 50 minutes on the phone trying to explain the issue, they sent a refresh signal and another code to deactivate this notification for the free subscription end. I even suggested to cancel the account and stat a new account for the year I paid it. However, all this didn't work as well. Finally my day of the free subscription came to the end last week and my regular subscription started and suddenly it is all good 👍 without any notifications, terms to agree to, and my Sirus favorite channel finally got saved and stayed on every time I turn the car off.
Bottom line, if you ever experience this nonsense, the simple answer is "do nothing and wait" till your official subscription date comes in. Enjoy!! 😉