From pro to free (Pre-sale question)

Hi

I enjoy the free version of Polylang. However, I really miss, as the only thing in fact, that I can duplicate pages and posts. I can see, that this can be done with the pro-version.
However, we really don’t need the pro-version for anything else. I would be happy to ‘buy’ the plugin but I can’t; as a number of plugins, this operates on a ‘pay again and again’.
Can I ‘buy’ the plugin (for a year of course) just to use it for duplicate my posts and only have it for the year out – and return to the free version after I duplicated my posts?

Thanks in advance

Mick

The page I need help with: [log in to see the link]