The oddly named protection device called a DONGLE was plugged into the Commodore’s tape port or the joystick ports. When the program would load it would check for this Dongle, if it was there the program would load, if not the program would not.

Here a list of Commodore software that I know used a Dongle as it’s form of copy protection.

10th Frame: used the dongle on the tape port
Coco
Coco 2
Insta-Calc (some version)
Leaderboard
Leaderboard World Class
Neutral Zone
Paper Clip’s dongle fits into the Joyport,

This type of protection is not disk based, but something that came with a game that you had to make up items on the wheel and enter data into the game for it to start.
So you could usually copy the disk easily, but need this device to play.

The most famous example is the code wheel from the Secret of Monkey Island.

Some others include

Bard’s Tale III
Monkey Island 2
Neuromancer
Out of this World
Pool of Radiance
Secret of Monkey Island
Zany Golf