How long can you look at 15 Euro Netflix?

I bought a 15 Euro netflix coupon and redeemed it with the worst subscription at 7.99. Can I then watch 2 months of netflix or do I have to buy a card again after a month because I have only 7.01 euro on my acc

Unless you have the free month with you (you get the first month for free as a new customer), you will have to buy more credits for the next month.

But the 7.01 euro saved on my account or?

Yes, they stay is then remaining balance

Yes.

Of course you have to buy a new card, or re-pay, you have a free month of 30 days, when that is gone, it will automatically be deducted from your account. You are right 7.01 euro remain, but if, of course, no 7.99 euro come together as the remaining balance. What did you expect now for an answer? You are missing 0.98 euro and Netflix will certainly not say that you get the free.

It goes on as normal, but then it is less than a month for a few days. For example I have a subscription for 13.99 per month and always buy 25 euro voucher. A whole month goes out and with deb debit 11,01 euro it goes on for about 20 days.