"So while the plugin would most likely work soon after NOT renewing the license, the downsides to not renewing would be very apparent after about 6 months to a year."

After seeing how often bug fixes are made to Woo Extensions I think 3 months at best, that's not even taking into account changes to WordPress or Woo Commerce or common plugins like Gravity Forms.

You could also be running several Woo Extensions where the update of one then impacts the other at it no longer works.