If you installed the RS Documents app trial and are ready to activate your licenses follow these steps.
Login to AppExchange and click your name in the top right, then ‘My Account’ or ‘My Installs & Subscriptions.”
It will show all the apps you have installed. Click the ‘Buy Now’ button under the RS Documents app (if adding or removing users after you already activated subscription, you will need to click “modify subscription” instead of the “Buy Now”).
Follow the steps to purchase the number of licenses you wish to purchase.
To assign licenses purchased to your Salesforce Users, go to your Salesforce, then to Setup, and Installed Packages.
Click “Manage Licenses” link next to the RS Documents package.
If using Lightning Experience, you will need to switch to Classic mode to see this admin setting to add/remove users.
Add and remove users to the app to manage the licenses available.
You can always return to AppExchange area to buy more licenses or less licenses.