Ask HN: Gave loan to startup which is now profitable. What should be repayment?

Hello HN, I am a small time angel investor and roughly 7 months ago I gave a long of $50K USD to a startup with no terms other than when the company is profitable the company will pay me back.

Now this is the second month that the company is now thriving and have Net Revenues of $1 Million USD.

It's time for repayment. What should I ask for? 2x, 5x, 10x loan amount?

I don't want to be outrageous or undervalue my investment. Just want to be fair and need some help in this area.

Thanks in advance