Is it possible to change the versioning system?

Hello everyone, i’m sorry i dont know which category i should choose.
What i mean by this title is : is it possible to keep like 15 versions of the same file in the versioning but they never expire ?
I’m really sorry for my english, i’m french.
As i understand, as time goes on, the amount files version’s decrease untill theres one left every week is it right ?

You can only define a time span, which can be infinite:

But it is only possible if the users still has enough free space. It’s not a good idea to use (and especially to rely on) this as backup.