wpDataTables - automatic updating

In May 2018 I purchased from Envato Market a regular licence for wpDataTables with 6 months support. I have been delighted with the product and have created lots of tables.

I was disappointed to find that updates to the plugin had to done manually. I posted an enquiry questioning this approach and was told that the development staff were working on enabling automatic updating. The manual updating works fine but is extremely stressful and takes a lot of time.

Recently my Wordpress Dashboard has been warning me that a plugin update is available but when I try this I am told I need to ‘activate my plugin’. I have tried to ‘Activate with Envato’ but I get a message that I don’t have a valid license. I have tried to activate by using the purchase code which I copied from the email confirming my purchase. Again I am told that I don’t have a valid license or it has expired. So it seems like although I have an ‘ongoing’ license I cannot now move to automatic updates. I would appreciate any suggestions of how I might proceed.