Shopify are asking people to choose NOW, if they want to use the Pro or Lite version at the end of the trial period.
But if you do choose the lite option, shopify changes you immediately to this version and stops all the Pro functionality. Not great when we are still unsure which version we want, but don't want to commit to the paid Pro version just yet.
This is despite all the blurb available telling you that no changes will be made until the end of October. (misleading to say the least)
So if you think you may wish to eventually switch to Lite - but are still not sure - you may as well wait until 31st October.