To update the plugin you don't need any particular operation.
Once downloaded the latest release from your reserved area, you need simply to upload and install the package using the Joomla Extensions Manager as usual. During the installation the extension will be updated and files overwritten automatically.
After having updated the plugin, no settings or configuration will be lost. Only the files will be updated, but all settings will be preserved.
Although to update the plugin it's only required to download and install the latest package using the Joomla installer, as long as you have a valid ongoing updates license you may choose to take advantage of the standard Joomla! Updater.
To use the Joomla! Updater it's required that you to specify exactly your email address used to register your account and perform the purchase on our store https://storejextensions.org to check the validity status of your updates license and automatically prompt you to download and install updates as soon as they are available.
Pay attention that if you are using the Joomla! auto updater the JSpeed plugin must be published and active.