Why I am receiving “Exceeded maximum number of activation”?
The number of sites where you can activate the key depends up on the theme plan you have purchased. If you have purchased single site license then you can use the api key in any one site of yours. If you want use the license key in more than one site then you have to either purchase 10 site license plan or All themes plan(unlimited site license).
If you want to switch the site on which your api key is being activated then you can reset the key activation from one site and use the key in another site. For example: If you are using the key in your staging or test server and later want to deactivate the key on your local server and use it in your live site then you can easily do that. You can reset the key activation from your account page.
Just log into your account page and under API KEYS section you will see the key and the site where it is activated. Simply click on the delete button next to the activated site link and you can activate the key on your new site.