Can I swtich Turbo Tax Online Premier to desktop

I have Turbo Tax online premier version (already paid). Can I switch to Turbo Tax  download premier version (I like form mode) and if yes how?

 

Would there be extra cost? Do I have to pay at time of filing or at the time of switch?

 

I used to use Turbo Tax Desktop. In the past when I had to access previous tax return, TT in most cases ask again product license number. It has been helpful that I kept all of my previous years CDs.

 

Now with this online version or download version, do I get some sort of license number for future use in case I need to access my tax return (I am not talking about accessing PDF version, I am asking about tax return within software as I know where most things are located)?