How long does a 25 euro Netflix voucher last?

I wanted to get a Netflix voucher then got one for 15 euro and it lasted 1 month now wanted to ask how long a voucher for 25 euro is?

Depends on your tariff. If a month costs 15 euro, then 25 euro only last a month.

Your voucher value divided by the monthly contribution, then round down to a whole number and you have the number of months for which the voucher is sufficient.