How to install Grid Kit premium (Licence Key)

Hello,

I had downloaded Grid Kit Premium for a customer several years ago. I believe at that time I had paid a single fee, but the plugin updates were not included. There are now critical errors in the plugin that could jeopardize my website if I don’t update it to a version higher than 2.0.0. I then bought the standard license, payable annually, in order to have unlimited updates year-round. I now have a license key. However, I can’t find where I can add this license key in the plugin? I tried to upload the new Grid Kit plugin to my website without deactivating the old one, but it gives me an error message on the screen and the plugin won’t upload. Do I have to deactivate the old Grid Kit Premium to activate the new plugin? Will I lose all the image galleries I’ve created? If you can help me quickly, I’d really appreciate it, so I can see what my options are for having a plugin that’s safe for my site and for not losing any of the galleries I’ve created. Thank you very much!