Generating Numbers/Text in certain way/form

Working on a script to generate a Key of letters/numbers in a certain way, I need to generate the key in a format like shown here xxxx-xxxx-xxxx, i would generate the key in replace of the xxxx-xxxx-xxxx like 19n3-m1m9-1nl1 but then generate this key in front of another string like Key=xxxx-xxxx-xxxx so Key=19n3-m1m9-1nl1 and loop it multiple times then save this string in a text file