A minority of users cannot provide a valid credit card for some time. It is annoying and not fair to expose those users who paid for their account to a constant and unremovable banner
My subscription expires in 5 months, so I will see this banner every time I log into my account. Have you thought about how this feels for me? I cannot provide a valid credit card for technical reasons. I will make sure I pay before my account expires, and you will still keep displaying this annoying banner.
Not very friendly, not very respectful of a long-time customer. But certainly insiring to look at the alternatives to Dropbox.