Netflix credit for Premium?

I want to buy a premium Netflix package (3 other people will be watching in 3 different devices). Do you know if that is possible? Or is it only possible for one person and one device?

Do not understand the question. The premium package includes the use of Netflix on multiple devices, by multiple people - they don't even have to live in the same household.

I mean, if I buy a netflix credit online (worth 50fr / euro) and the premium package (think it's 20 fr / euro) whether that works? So that I buy the premium?