Running Adobe Acrobat XI PRo

Hello!

I hope you are doing well.

As our community expert correctly mentioned, Acrobat 11 has reached its end of life and is no longer supported. For more details, refer to this article: [link]. You may try the suggestions provided in the article, but they may not work.

Thanks,

Anand Sri.

If you deactivate it you won't be able to use it again, as the activation servers have been discontinued by Adobe.
I can't say for sure whether upgrading the OS will cause it to stop working. It's a chance you'll have to take, I guess...