The Herzum Attachments Manager is the app for Atlassian Jira that let you define a limit on the attachment size specialized by project and, furthermore, a limit on the number of files let be attached to the issues always specialized by project.
Notice that the app overwrite the default Jira maximum attachment global configuration (Jira Attachment size).
A fully illustration of the mentioned features has been detailed on the following pages:
The mentioned configurations can be applied together or singly, as per the illustrated examples, by introducing a negative number on the limit to be unrestricted.