I asked for clarification on Facebook, and have not gotten an answer in the past 50+ hours, so I'm asking here.
The instructions I was given are:
"To properly use the code you will need to be in Deluxe or higher. Follow these steps:
1. If 2017 has been filed in the account click on "Add a State" on the "Tax Home" page.
2. In the left hand side bar choose "Upgrade".
3. Confirm the upgrade
4. Go to the "File" tab in the side bar.
5. on step 1 "Review your Order" click revisit/update.
6. Scroll all the way to the bottom and click on the blue link "I have a Service Code".
7. Enter (my code) exactly as it appears here. (You may be prompted to register your product if so do it.)
This will give you access to all prior year returns in the account. "
