There are no lifetime subscriptions. They are annual fees. If they did not pay their annual renewal fee for premier they will not be able to upgrade nor have access to premier features. If I knew the name on the account I could check to see if they have an Active Premier subscription. It is a $275 a year renewal fee to maintain the Premier subscription
You might need to deactivate Power and download it again from their account once that is done you would delete the old version and upload the new one manually. I do not know about Premier, as I mentioned, I cannot see if they have paid their renewal fee without additional information.
Search by name is done with the Experience add-on
https://docs.storelocatorplus.com/blog/search-by-name/