One plugin will not update

Hello. I have a plugin that we purchased (User Role Editor Pro) that will not update. The plugin author sent me two links to WordPress Codex which are Greek to me. I don’t have time to mess around with this. Purchased plugin and it won’t update? It’s literally the ONLY one on the whole site that won’t update.

Can anyone offer some advice/experience on this? Why would ONE plugin have permissions problems?

Thanks in advance for any help or ideas. Much appreciated!