Today its only possible to configurate the Build expiry by saying the number of days to keep. In some cases I would like to set it to keep the last x builds. Or an alternativ to this is to possibility to mark some builds to not be expirable.
An example of this is for projects that are finished and no one is working for a while with the project. It would be nice to still have the last builds. And in some cases to have some builds from milestones in the projects stored.

This is not a big issue, but a nice to have feature imo.