why do I have to pay to file state taxes when I paid for the product with one state?

Did you purchase desktop software with state software included?  They sell Deluxe both with and without state software--so you have to be careful which one you choose.  And even if it does have the state software download included, that is for preparing the state.  There is an extra fee to e-file the state.  You can avoid the $24.99 state e-file fee if you print and

mail the state instead of e-filing it.

Some states allow to file taxes online.

See this article to see which states offer that: https://www.creditkarma.com/tax/i/fi[product key removed]-for-free/

This way, you can prepare your taxes using tax preparation software and then use your state's website to file your state taxes.