Not an easy way afaik :/ but if someone knows a good way please let me know
1. Whatever limit I put needs to be completely arbitrary. 5$? 10$? 2. I cannot guarantee they will use it correctly. They might use it for the challenge. They might use it to generate harmful content. 3. It requires me to manually create and revoke keys. Candidates might want more credits. They might get leaked.
There are solutions. I just can't think of good ones.
I think “we offer a $50 (or $20 or whatever) Visa/Amex gift card as part of this interview step” is easier to admin, might skate by finance more easily, and avoids all the tech support angles of “here’s how to use our specific tooling” and concerns of them misusing your key for something nefarious.