Limiting max usage of API or Pre paid account

currently I am still using the API under the free trial, but would like to set up a paid plan. I have a single worry, currently it is not possible to simply top up my account with money and use up that amount, instead the total amount which needs to be paid is withdrawn at the end of the month. Now, I am afraid that, if somebody hacked my account or got access to my API keys, would result in a huge bill for me. I know that AWS is working in a similar fashion, but at least I can set up alerts there. Any opinion on this?

Edit: looks like the pay as you go option is limited to 120$ per month, so this is exatly what I want, also notifications can be set up on OpenAI API