I too got the free version first, and then moved to the pro version, but did wait to do anything serious with the pro version. Perhaps you could create a dupe site and test there.
Let me know if you need some help with that – not hard but does involve a number of steps.
Otherwise – just backup the whole site – database and WP stuff. If you have to fall back – at least you’re covered. I think you can install the pro and free versions – just keep one disabled.
When you disable the plug in, naturally the features done with it will disappear. But knowing software – I suspect there is little FUNCTIONAL internal difference between the two – and when you enable the pro version, I think everything will be there as it is now – with access to the extra modules.