Since you now have to log into an Intuit Account when you first install it, all your downloads and licenses are listed there (even if you bought it from somewhere else) so if you need to install it again or install on another computer, even on the other operating system (Windows, Mac) you can download it again here,
https://accounts.intuit.com/app/account-manager/productsBilling/turbotax
For Windows…..What I would do on the old computer, is copy the whole Turbo Tax folder that is under your Documents. That should be where the .tax files and pdf files are stored. Also if you haven't done it, I would open each year in the program and save it as a pdf file, go to FILE - SAVE TO PDF so you don't need the program installed to view your return. Copy that folder to a flash drive or best yet is to burn it to a CD or DVD and then you will have a backup of them. Then on the new computer copy the folder (or files) from the flash drive to your Documents folder.
You only need the tax return data file ending in .tax2023 to transfer into 2024 or .tax2024 to transfer into next year. You can't transfer the programs. They have to be installed from the CD or Download. You don't need to install older programs unless you need to amend or you didn't save the pdf file. And they only support the last 3 years. If you install an older year you won't be able to update it or download any state programs, so you won't be able to open your return.
See this article on how to move your tax return to another computer…….
https://ttlc.intuit.com/community/tax-data-file/help/how-do-i-move-my-tax-data-file-to-another-compu...
IMPORTANT
After you get the program installed or reinstalled the first thing to do before you open your tax return is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW). Enter some basic information, then go to the state tab and download the state program. Then try to open your existing return, go to FILE - OPEN
