If you log into your account at https://my.roku.com you can create or reset a PIN value. You can then choose when the PIN is to be required, such as before it will allow any subscription or purchase to be made on your account.
Be sure the email address you use to log in is the same one shown on your Roku via Settings / System / about.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X