If you buy the Desktop CD/Download program you don't have to register it. I never do. You can transfer from 2019 if you have the .tax2019 file on your computer. Did you use the Desktop program last year too on the same computer? Or where is your 2019 return?
How to transfer into Windows Desktop
https://ttlc.intuit.com/community/entering-importing/help/transfer-last-year-s-return-to-turbotax-fo...
How to transfer into Mac Desktop
https://ttlc.intuit.com/community/tax-data-file/help/how-do-i-transfer-last-year-s-return-into-the-t...
