After canceling your Nelio A/B Testing subscription, and once the contract period has elapsed since the last payment, your premium version will be deactivated. On your site you will have the free version of the plugin. The accumulated visits will be lost and the available quota of the free plan (500 visits to pages under test) will be re-established.
All the tests and results of the previously executed tests will still be available but, please note that as soon as the available quota of the free plan runs out, the tracking of visits on your active sites will stop and will not count for the tests you have running.