What does it mean when I try to udate the default sigma theme and it tells me I am missing the product key? 

Isn't this a free theme? 

Osclass version 8.0.2

Tried typing missing product key into search and got lots of posts but nothing pertinent to my question.

@nootkan

It is free but if you create a profile on https://osclasspoint.com/ and enter the domain where you are using the script a random product key is generated wich you can use in your admin. After that you can visit the market from admin panel and download free or payed plugins.

@nootkan
I can see product key defined in index.php of theme.
Anyway, latest version is always in latest osclass version.

@nootkan

It is free but if you create a profile on https://osclasspoint.com/ and enter the domain where you are using the script a random product key is generated wich you can use in your admin. After that you can visit the market from admin panel and download free or payed plugins.

Thanks for your reply.
Already done all this.  I was just trying to update from the admin backend.  It seems it won't work when using wamp on my local server. 

@nootkan
I can see product key defined in index.php of theme.
Anyway, latest version is always in latest osclass version.

Thanks for your reply.  I already have the latest version of osclass installed.

Tried just updating with version 8.0.2 over older version 3.8 but too many issues with previously purchased themes and plugins so I installed fresh version 8.0.2 on wamp and started transferring over users, items etc.

Developers of older version osclass themes and plugins are no longer supporting what I paid for so now I have to start over.

I'm guessing the sigma theme update has something to do with my local wamp server not recognizing the api key.

Might try the Sophia theme instead to see if I like it better. 

Thanks for the replies but I will update theme(s) when I go live and see if the issue still exists.

Product key is set in index.php of theme/plugin and is simply unique identificator of product, so it is easy to pair it with updates.