Hi @Els - just checked with membership services and yes, they can still leave a review. Here’s what Carla says…
“Yes they can still leave a review as an expired member. They should login and in the drop down menu under ‘renew’ they will see the review option and can leave a review as long as the sit was originally confirmed on the site.”
Of course the happiest outcome would be they carry on using house sitters 
Where to next Els?