Good for you if you are making that much but check this post first.
Paying for Gdevelop Pro if you have a revenue of 50.000k a year? - GDevelop general - GDevelop Forum
If you are indeed gonna make that much I don’t think that giving the engine a small amount of money is a big issue. They are the main reason that you are earning them anyway.
Other companies such as Unity are asking for a percentage from your profit, which is much much more.