It sounds like emails from us are not getting through. Your account was downgraded because your credit card was declined three times. You were emailed twice about this issue. Once after your card was declined for the second time and once when your account was downgraded. The fact that you did not see these emails and are not getting forum alerts suggests that you either need to update your email address on the Settings page or that email from LingQ is ending up in your Spam folder.
I’m afraid there must be something wrong with your email. I sent you two emails myself about this to your email account in our system. If it isn’t in your spam it must be lost somewhere else.
If you input your credit card information again, it should be fine but please make sure your card has not expired or had some other Change. Your previous card was denied this month.