Welcome, @holiday55.
Thanks for your first post here in the Roku Community!
That's a great question! You can access other people's paid accounts (with their sole permission) to watch ad-free movies. To access the content, simply visit the streaming store and download the stand-alone app.
Rest assured that even if you have connected your payment information to your Roku account, you will not be charged for subscriptions that belong to other individuals. You will only be charged for a subscription if you were the one who initiated the subscription and it was linked to your Roku payment method.
For future reference, you can manage your own subscriptions by visiting this support article: How to manage and cancel a streaming subscription.
Let us know if you need further help; we can assist.
All the best,
Emman
Emmanuel-D.
Roku Community Moderator