Netflix payment methods?

I have the problem that I still have 7 euro in credit, but membership costs 7.99 euro.

Can I pay the rest of the 1 euro through my account or is that not possible?

If the credit is on paypal Dan it works. The 1 euro would then be deducted from your account by paypal

But let's assume I only had the voucher, would I still be able to look at it for a whole month with the 7 euro?