Hi James!
Our plugins and themes will continue to function normally without an active Premium subscription and your websites will not suddenly fail if you choose to let the licenses, so no worries there! However, there is specific functionality in both the Post and Page Builder and Total Upkeep that you will no longer have access to.
In the Post and Page Builder, for example, you will no longer be able to use Premium only blocks in through the Add Block interface, but any Premium content that you previously will still function and won’t suddenly break without an active Premium license. In Total Upkeep you will no longer be able to use 3rd party platforms like Google Drive and Amazon S3 for storing your backups, but you will still be able to generate and store backups on your web server.
All of that said, as a Web Hosting Hub customer you should have been provided with a Premium Connect key that is valid for as long as you continue to use them as your hosting provider. The only Connect key that I was able to find associated with your email address appears to be one from them and does not have an expiration date associated with it, do you have Premium licenses that were purchased with an alternate email address that are set to expire soon?