They're earned by completing college courses

Usage examples of credits.

As soon as the credits began to crawl up the screen he retreated upstairs to talk to God and his grandmother.

As the film continued I offered small talk, made Denise vague promises that I would see her in the morning, and left as the credits rolled.

Sabine system imposes a fine of five thousand credits for improper undock, and you have an outstanding ship balance due of 2345 credits for docking services.

She took the hardcopy of the contract, flipped through the pages, and wrote in the margin an addendum specifying 100,000 credits compensation for the death of crewman Gary Tobai, signed it, and slid it across to Kalin for his initials.

He played the hand to the limit and, even with the low stakes, eventually raked in about four credits in coins.

He had won forty-five credits, and knew he had better quit before he caused irritation.

Give him fifteen credits and let him regard it as a personal loan from you.

The fifteen credits the weapon shop girl had given him would tide him over for a few weeks.

It was a big bank in which to deposit the tiny sum of fifteen credits but the money was accepted without comment, though he was required to register his fingerprints.

For instance, a lieutenancy would cost you five thousand credits even with my influence behind you.

If he could win five thousand credits and buy a commission, the treasures of Isher would start pouring in his direction.

He recognized that this luck was phenomenal even for him and long before the hour was up he was risking ten credits in each channel that he played.

At intervals, he would thrust a handful of credits into the automatic changer and receive large bills, which he would press into an inner pocket.

When he had won uncountable thousands of credits the doors of the Penny Palace closed and the roly-poly man came over and spoke curtly.

The thousand people in here now are hired for such occasions and cost us ten credits each.