If you have the original I guess it is locked, you cant lock a Garmin map, or probably it can be done with Mapsource Product Creator, try .
Actually maps need a .gma and an .unl file to be authenticated and unlocked. The .gma file can be created just by Garmin and it works on just one unit.
The alternative is the unlocker, but it unlocks, it cant lock ,lol-
Any hope you can share that map?

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I want to lock/secure the map.
What do you mean with lock/secure the map? The original is locked: what do you need more?
Cant resell locked Garmin maps coz cant create .gma and I agree