Hello. I have a flow that adds a watermark to a pdf. For this, I'm using plumsail.

This works fine, the only issue is that I am using a trial subscription and once it expires the flow no longer works. Is there another way to add watermarks to a pdf but for free?
I looked at all of the options given by flow and from what I could tell, they all seem to require a paid subscription to continue using.

Is plumsail the best one out of these? Is there a way to do this in Flow without a paid subscription? Thank you.