I cannot restore my previous purchase
On some occasions, the “Restore Purchases” button does not work as expected. You can use the “Purchase” button instead.
Before you proceed, you want to make sure that the previous purchase is indeed registered with your current iCloud account. Refer to these instructions on how to do that.
Once you see “Dropover Pro” in that list, you can safely select the “Purchase” button. As the purchase is already registered with your iCloud account, the system will restore it for you. You won’t be charged.