A reasonable strategy would be to stop charging customers who haven't watched in a while, but leave them enrolled as subscribers. If they start watching again, start charging again.
I wonder if it is different if you were never a paying user? I did the free trial in February 2019 and then cancelled. If I try to login now, it starts going through the whole set up a free trial for a new user process, with no indication that it recognizes my account.
In fact, if I try to login with the email address I used for the trial and any random thing for the password, it goes to the new user trial setup.
If I hit thee "need help" link on the sign in screen and try to initiate a password reset, it tells me there is no account for my email address.
