Hi! Thank you so much for pointing this out. Thought I was pretty good about memory management in there, but I must have missed something. I am going to try to get this sorted out and hopefully have a fix out in the next week.
Viewing post in GMS2: Grid-Based Pathfinding Scripts comments
I have just uploaded version 1.1 of the scripts and reference project! To my knowledge, all the memory leak bugs have been fixed. In a test project, I called all three algorithms every step for 5 minutes straight and saw no increase in memory usage. So hopefully this will solve your problem.
I apologize for any delay this might have caused in your development. As always, if you have any more issues with the scripts, you can post again here or message me on Twitter.