[alwaysclosing]

Screw the variable payout notion. It's a hook (as said).

- $6m in 3yrs is a substantial risk and unlikely due to what everyone else said.

- $4m in 2yrs is still a decent time horizon, but as mentioned, they are trying to lure you in for on the promise that it will be hard to pay in 1 year and probably more than they are prepared to spend.

- Try $3m in 18 months with $1.5M upon close and $500k divided over the next 18 months.

You get 75% upfront and can hedge on their success/failure.

Waiting and anticipating checks to arrive is a nightmare and if you are like most, you will be highly bothered by this - whether or not you get your code back. (At which point, it will likely be duplicated elsewhere or deemed irrelevant.)

[bootload]

"... Try $3m in 18 months with $1.5M upon close and $500k divided over the next 18 months. You get 75% upfront and can hedge on their success/failure. ..."

Nice answer.