If TurboTax Premier 2018 includes 1 state tax why am I getting charged separately as I try to file?

When you use Online TurboTax, you get one return per fee.  Each return needs its own account and user ID.   If you use the same account and user ID for a second return, you overwrite the first one and lose it forever.

 When you use Desktop TurboTax, which you install from a CD or download to your own hard drive, you can prepare and e-file multiple returns for the cost of the software.  You can e-file up to 5 Federal returns—more if you mail the additional ones.  If you have multiple returns to prepare for family members, Desktop is more cost effective.

https://ttlc.intuit.com/questions/1901306-how-many-times-can-i-e-file-using-the-turbotax-cd-or-download

https://ttlc.intuit.com/questions/2942039-what-s-the-difference-between-turbotax-online-and-the-turbotax-cd-download

https://ttlc.intuit.com/questions/2750704-what-are-the-advantages-of-the-turbotax-cd-download-software-over-the-online-version

Online Premier does not include the state for free.  With online you pay extra for the state.  You are posting from online software.  If you used desktop software from a CD/download, it would have included the state.