I just did something that got the license activated on my Windows 11 computer using Studio One Professional 3. I will try and remember what I did.
So first, i was unable to log in to my account from the studio one activation portal where you search and select for the product key. What i did was, using the same computer, log in to presonus.com site and find the activation menu for licenses. I deleted one that was named similar to what i was using (i know i am only using 3 licenses right now and 4 were listed, probably old laptop) i then clicked on "OFFLINE ACTIVATION" under the software I wanted to download and then "ACTIVATE SOFTWARE".
From there, I determined my computer's name and copied this name exactly into the "Enter computer name tab"
Now, i went into the Studio One software offline activation part and copied the activation code listed there and pasted into the "enter activation code" tab back on the website"
I then clicked "DOWNLOAD LICENSE" from the website and opened up the file location. I opened up the Studio One Software again. I found that selecting the downloaded license from a folder did not work and caused and error but when I dragged the license from my files onto the Studio One software window, it immediately said that my software had been activated.
I hope this works for someone. I am glad i was able to troubleshoot it because have a gig tomorrow that i need my software for live show. You might have to try this once or twice to allow the software to refresh but it worked soon as I did everything i mentioned and dragged the file versus selecting from tab.
THIS METHOD DID NOT REQUIRE A SECOND COMPUTER: done right from computer I wanted to activate.