Once you open the packet ham the opened packet ham should last from 4 to 7 days if you refrigerate it.
Once you open the packet ham never leave it out longer than a couple hours and refrigerate the packet ham if you're not gonna use it within 2 hours.
If you leave the opened packet ham out longer than 2 hours at room temperature then bacteria can start rapidly growing on the packet ham.
You can keep the opened packet ham for up to 6 months if you put it in the freezer.
Freeze the opened packet ham if you're not gonna use it within 7 days but any less than that you can just refrigerate the opened packet ham.