That never works for me. I try to only sign up for things that I can cancel immediately and continue to use for the rest of whatever time period I signed up for.

Instead of potentially getting billed for some trial I forgot about, I would rather pay for a month, immediately cancel, and then repeat every month when I realize it's not working.

Besides helping me keep my expenses under control, it doubles as an evaluation of the company. If they make it difficult to cancel, or do not let me use the rest of my paid time, I know they are not a company I want to do business with.

That seems like a decent strategy too.