"premier service licenses don't have activation keys"
I am concerned you might be mixing two issues. Single-user Professional licenses for Windows and Macintosh Mathematica have used Activation Keys since version 8.0. Premier Service is about the help available, when.
A big operating system jump might have changed the MathID, which is part of the password-generation process. If the MathID changed, then you will need a new regular password for your regular Mathematicas.
Customer Service (firstname.lastname@example.org, 217-398-5151) is the place to obtain regular passwords.