$8.00 a month to use it too. No thanks.
If you do not download the design and just copy the design, you do not need to purchase a license. On the other hand, it might be worth the price if you need a tool like that. Bottom line is supply and demand. If the creator does not receive the amount of use and revenue he was expecting, he will change his use fees.
I think with all the features already in LightBurn, it could be quite feasible to include the same kaleidoscopic functions as in Polygonia. Can make a killer application for small laser business. One can create nice looking items literally in seconds.
If you agree, you can upvote this feature suggestion here: https://lightburn.fider.io/posts/656/kaleidoscopic-pattern-like-polygonia-design