Lightroom does not have a "save" command ... but you should be able to Export your photos to any location you want, just change the location in the Export dialog box. There is no moving of photos necessary.
I don't know whaat you mean by "personal use". it sounds like you are saying that the photos in your library are now on the zip drive ... is that what you are saying? If so, then reverse the process, move the photos back to their original location, and then export the photos to wherever you want them to be.
What option did you selected while importing Pictures? Copy Move or Add
The Pictures Will be available to you in Library if you select Copy and Copy as DNG
If you select Move and Disconnect your External Drive .Pictures will show up missing with ! sign in Lightroom
Also the correct way of importing Pictures is to add them to catalog and keep a copy in your External drive.Not essentially Copying Pictures to External Drive.
- If you import while keeping TO destination(on top Right as shown in Picture below) as your Hardrive.You will have to keep your External Harddrive always connected to Computer
2. If you import keeping TO location as Default(Pictures/Lightroom/Catalog) or on you Internal harddrive.And Make a backup copy to External drive.This way you will have a Copy of your Pictures to access from Catalog.
Let us know if that helps