The free trial version has no time limit, but does not allow saving project files. If you have paid for the full version you own it now, which includes access to any future updates at no extra cost. Now that you've confirmed that saving the project prevents the export G-code crash I know that the fix I've put into v1.33a should work. I'm putting the finishing touches on v1.33a, mostly just updating the user guide, and then I'll be putting that out over the course of the day.
Feel free to share anything you create with PixelCNC that you carve on your machine!