The premium package is lifetime license that mean if you download and install the license didn't require any monthly or annually fee.
Our developers work with love and efforts to make the product better and make the bug free updates available to the customers. These updates are provided for 6 months free of charge when you purchase premium social network. This includes some other services like mobile api , sentimental api.
If your 6 months period expired our system asks you to renew the support to download the updates. You can renew and get the updated version.
If you wish to upgrade only core you can get download the core framework free of charge but note that this core update didn't contain premium updates.
v5.6 Core Update : https://www.openteknik.com/cores/core-v56.zip
v6.0 Core Update https://www.opensource-socialnetwork.org/download_ossn/latest/build.zip