Here are the steps after downloading the plugin and testing the free version:
Retrieve License after Purchase
The first step after purchasing PlumePack is to retrieve your license. If you bought it here on this website you should have received the code on the purchase confirmation page and by email ; for example it would look like this:
If you bought it on aescripts + aeplugins, a different reseller, please follow this article.
In order to remove the PlumePack Free version limit, you'll need to license it in the Settings popup: this is where you'll also find the PlumePack global settings (such as writing logs).
How to License PlumePack
Once you have your license code, you need to enter it from the "Settings & License" popup.
In the Settings tab you can paste the license you copied at the first step. If you're on Mac macOS you can use the "Paste Clipboard" button because COMMAND+V is not working.
Click the Activate button. Please note you can enter any license for any Autokroma product here
Click OK and restart Premiere Pro and you shouldn't be in Free mode anymore