Hi,
I think you know, but please let me describe it!
You need to download from JoomShaper website the Pro version of SP Page Builder and then install it over the lite one through Extensions>Manage>Install.
You will get all related info there:
https://www.joomshaper.com/documentation/sp-page-builder/sp-page-builder-3/installation
And please make sure you have 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. and then clear your browser and Joomla cache.
Most importantly, You have to copy the license key from your Joomshaper Dashboard. I have attached a screenshot for your ease:
https://prnt.sc/vesh66
Hope it helps!
Best Regards