I own Infuse Pro 6 Lifetime, cant upgrade to free 7 Pro

That is the standalone Infuse 6 Pro and is good for all updates up to but not including V7.

You can continue to use that one as long as future updates to the OS or APIs don’t cause issues. Then you would have to start an Infuse subscription since starting with V7 there is no longer a standalone app.

You can read more about this here. It’s a long thread but it addresses most all questions.