This is from the perspective of the company so you'd be 40k in the hole. You'd want something like
"Upon agreement to the terms the licensee will receive forty thousand US dollars ($40,000) within ninety (90) from the licensor. There will be a penalty of one thousand US dollars ($1,000) for every day after that period if not paid."
You get to pick. 90 seconds, 90 minutes, 90 hours, 90 days, 90 weeks, 90 months, 90 years, 90 rotations around the Milky Way Galaxy, 90 cycles of the Big Crunch/Big Bang, 90 iterations of God, 90 iterations of whatever made God, etc...