If you didn't purchase Studio One directly from PreSonus and cannot register it to your user account with the product key provided to you, create a support ticket so that we can help.
If you did purchase it directly from us, it's already registered in your user account and you only need to activate it.
Follow the steps below to activate your product.
1. Go to menu Studio One > Studio One Activation.
*** Step one above may or may not be applicable depending on if you have already activated a version of Studio One like perhaps Prime. If Studio One launches directly into a login screen be sure to login with the credentials for this account. After that, follow the step to Activate Online to get to the activation screen.
2. Check the option ... "Activate my purchased version of Studio One" in that dialog.
**** Do not check the box "I have purchased an upgrade of Studio One****
3. Click the downward facing arrow on the right edge of the list field there to refresh your product keys listing "Show My Existing Product Keys". This will retrieve your registered products from your user account. If you don't see it listed this means it's not yet been registered to your account or you are signed into the wrong account.
4. Select Studio One 3 (whatever version you own) from the refreshed list and click "Activate" and it will activate the new license and restart as Studio One 3 (whatever version you own)