For the most part, you can cancel a subscription at any time and use the subscription up to the date of renewal. (since there is no pro-rating, generally.)
As such, you "should" be able to reinstall the Channel/app, login/enter your credentials and continue to watch until your subscription expires. (Just don't click on anything to re-enter your billing info or anything that extends your subscription.)
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941