... if you have all the ultimate PDFs from before the changes ... far as I know (but ultimate users will get these for ... to the changes as an ultimate user so I can probably ...
... Premium: Easy problem sets
* Ultimate: Easy/Medium problem sets
* Ultimate will probably have roughly the ... New questions.
* Ultimate+ will probably have more New ... than Ultimate had Old.
< ...
You can upgrade but it just upgrades your amount of access and does not increase the length of that access to the full amount of the higher package. You would then have to buy the necessary extra months separately. Upgrading only adds a month IIRC.