The PDF is for your records. After 6 years Turbotax deletes the xxx.taxyyyy file. after 3 year including extensions the xxx.taxyyyy can no longer be opened and even with the desktop the app cannot be reinstalled nor will it open an old xxx.taxyyyy file. your only source for what was filed is the PDF file of your tax return. Note that a PDF cannot be e-filed. it must be printed out and mailed in. in any case after 3 tax years expire, if you haven't filed the return for that year and are due a refund you can no longer collect it. you have made a nondeductible gift to the Federal government.
