I've tested it in FS9 and the unlock function seems to work fine. I tested this using the file Orlando.bgl, found in the Scenery/NAME/scenery folder. It is locked by default to the Orlando area. After selecting all the objects in the object list and clicking the Unlocked button, I get a new Orlando_Unlocked.bgl file created.
Using this unlocked BGL file in place of the default file allows me to use Instant Scenery to place an object from this file (in my case the Fantasy DC-3) at both Orlando and New Orleans. It appears in both places when I restart FS and check at both airports (you must test after you have removed IS from FS by restarting FS). When I then replaced the unlocked BGL file with the default one, the plane no longer appears at New Orleans but does appear at Orlando, demonstrating that it is indeed now geo-locked.
NOTE: At least on my machine, I had to restart FS between each airport test. If I went to Orlando first (using the geo-locked BGL) and then simply used GoTo Airport to go to New Orleans, the DC-3 was still visible there. I had to restart FS and then it was not present. And then if I just used GoTo Airport to go to Orlando, it wasn't there either. If FS displays it at one location it will display it everywhere else, even using geo-locked BGL files. Conversely, if FS doesn't display it somewhere far away, it will not display it anywhere else, even within the geo-locked area. You must restart FS to see that.
However, there does seem to be a problem with geo-locking an unlocked file. I started with my Unlocked Orlando BGL file created above, and then geo-locked it using (with DD.dd chosen):
Lat: 27 29
Long: -82 -80
When reloaded into GeoLock it yielded the results seen in the attached image.
As you can see, I am within the geo-lock coordinates, but there is no fantasy DC-3 there (which would fill up most of the screen). Furthermore, IS reports that this Orlando_Locked.bgl file is not available in this area. I can force IS to display it in the listing so I know it is present and contains all the objects, but it is not available in the Orlando area.
So something must be wrong with the geo-lock coding, I assume? I'm not sure what, though. I did check at -28 and +81 in case it was a minus sign problem, but no luck in any of those combinations.
Hope this helps,