How can I add my purchase downpayment for previous year, while I have only received the product and paid the rest this year ?

Down payment for what?  To buy a house?  What did you purchase?  You have to buy a separate Turbo Tax program each year.  You either pay for the online version or buy the Desktop CD/Download program at full price, no down payment involved.

I am sorry I wasn't clear.

I have an LLC that I established in 2019 and paid downpayment for products that I will resell in 2020 and paid the rest of the cost in 2020 and received the product in 2020. How do I report my 2019 downpayment as an expense ? Thanks