It is a question and a contribution to the community. I have the perpetual license of Adobe 2019. I had to reinstall it because printing in doc did not work.
From the Adobe support service they have downloaded version 11.8 to my mac. Now I find that it tells me that I have to pay again because the version that I have for my license is 11.5. They only give you a 30-day trial license. Support told me not to worry, they would fix the license issue for me because I had already paid for a perpetual license for Captivate 2019.
The problem is that files made with 11.8 cannot be opened in 11.5.
All the work of a month you do it again or pay the new license.
You pay for new licenses not for new functionality but for being able to continue with your work. I don't think it's correct in Adobe.
Personally I am still on version 11.5 and I am a bit astonished because recently I did a consultancy job for someone using 11.8 and I had no issues opening that project on my system. Even though I am on Win10 and the client on Mac.
You needed 11.8 probably to be compatible with the most recent Mac OS or because you use a M1 chip? Since 11.8 is subscription only it couldn't be installed as update on a perpetual license of 11.5. Personaly I agree with your frustration, this is not really customer friendly...