The only TurboTax products currently available are the desktop CD/Download editions which have to be installed on a personal computer. If you are referring to those products, then you can create and complete as many tax returns as needed. One free state program download is included in the purchase price of the desktop editions purchased from TurboTax (except Basic)
The Windows Vista operating system is not supported by the TurboTax 2017 desktop CD/Download editions.