You can always upgrade from Single to all other Semplice Edition, of course it’s also possible to upgrade from Studio to Business.
First of all navigate to http://www.semplicelabs.com/get-semplice and hit the ‘Upgrade for 39$’ button if you want to upgrade from Single to Studio, or the upgrade buttons below the Business purchase if you want to upgrade to Business Edition.
You will need to have the License Key of your current Edition in order to start the payment process. After you finished everything you will receive an email with a download link and also an order confirmation email with your new license key and your new order ID.
The easiest way to update your existing Semplice edition to your new edition is to just enter your new license code in the ‘General Settings’ to activate the one-click update. Make sure to select the right license from the dropdown menu. If you successfully activated the one-click update you will get an update notification which will download and install your new edition for you. Quick and easy.
Of course you can also update your Semplice manually, please take a look at the ‘How to update manually’ section in this guide: http://help.semplicelabs.com/customer/portal/articles/2298943-how-to-update-semplice