So if you share your pictures w/friends and family, they will show up in their Photopass "stream". Once there, your friends/family can do whatever they want with them. Edit, buy the download, order prints, etc. Any edits/deletions you do won't be reflected in their account. So if you don't want them to see your pictures, you would need to remove that ability from the friends/family link. If they are still set to share their picture with you, those will all show up in your Photopass to edit/download/etc.
This doesn't have anything to do with having Memory Maker. Memory Maker just gives you the download entitlement. Your AP lets you download them for a year, and they stay active in your account for a year as well. This year window does expire if you choose not to renew your AP however. Without an AP, they will expire after the time period shown with the picture.
Does this help?