Well since you can't buy Plus for 2017 now in 2019 you must have paid for 2018 Plus to unlock 2017. Did you pay for Plus in the same account that 2017 is in?
Or did you buy the 2017 Desktop download?
If you paid for 2018 Plus you can Contact Customer Service 5am-5pm Pacific M-F
https://support.turbotax.intuit.com/contact/
