To edit a Hosted Service in ArcGIS Desktop, you can create a local copy for editing.
When you do this, behind the scenes ArcGIS Desktop and Portal are actually performing Geodatabase Replication in order to facilitate this and by default, a File Geodatabase is used for the replica.
Assuming that you're using the default File Geodatabase option and not storing your replica in an Enterprise Geodatbase, then once you synchronize your changes, the metadata cleanup process is performed and your local copy is disconnected from the Server.
My question is, what would be the maximum age (if any) for a File Geodatabase replica that has never been synchronized to the Server before it is disconnected from the server automatically?
For example, if I created a local copy of a hosted service (assuming all default options and the replica is a File Geodatabase) and then proceeded to make my edits over the course of 4 months never synchronizing my data back to the server even once. If I attempted to synchronize my changes at the end of that 4 months when my edits were complete - would the synchronization process fail simply because my local copy is so old?
Is there a defined amount of time upon which a local copy is automatically disconnected from the server?