Hi,
First you have to download SP Page Builder Pro from here
https://www.joomshaper.com/downloads/extension
Then you have to install it. Go to administrator-->extension-->install
After that you have to activate it. Input your email and license key to SP Page Builder -> Pages -> Option (on the right) -> License & Update (input your email and license key) -> Save and Close.Your License Key is located in your Dashboard.
Then Clear Joomla and Browser cache.
For more help you can follose this documentation below:
I have the Pro version but with locked PRO features
NOTE: Make sure you have a full site backup before making any changes.