Yes, you can download your partially completed online tax return to your computer and finish it with the desktop software. The FAQ at the following link tells you how to do it.
https://ttlc.intuit.com/questions/1901476-how-do-i-switch-from-turbotax-online-to-the-turbotax-softw...
If you do this, and do not pay for TurboTax Online for 2016, then on October 16, 2017 you will permanently lose access to any saved online returns from prior years. So you should download the PDFs of any prior-year returns and save them on your computer before that date.
