If you have purchased uiPress pro then you will have received a licence key. Adding this key will allow you to unlock all the pro features of uipress.
Once you have installed uiPress pro on your site, go to the uiBuilder and enter the builder. Once the builder loads it will ask for your key in the bottom of the screen.
Paste your key here and press register, if you key is valid and hasn’t reached it’s activation limit it will then register and unlock the pro features.