Ok Tatar,
This function should be able to work for you. I’ve made it as a custom plugin, so just copy the contents of this Gist to your plugins folder into a new file, activate the plugin, then you can use the edd_ck_commenter_has_purcahsed
function in your theme or code.
https://gist.github.com/cklosowski/00ac09551933912137af
How I tested was I activated the plugin, and then added this function to the comment callback in my theme to verify that if a commenter has purchased the specified meta ID, it returns true or false.
As a note, this isn’t the most performant way, as it runs multiple select queries, but it is faster than the number of JOIN queries we’d have to make to get this data in a single query.