WP Experiments will be back soon!
In November of 2018, WordPress 5.0 will be released. This new version of WordPress brings with it the new Gutenberg editor. Title Experiments relies heavily on the old editor of WordPress and will not be updated to support Gutenberg.
Therefore, Jason, the former owner made the decision to stop selling Title Experiments Pro and will not be supporting the plugin on WordPress 5.0+ going forward.
But under new management – WP Experiments will be back soon.