Follow these steps to assign Subscription25 licenses and Permission Sets to your users
Assign a Subscription25 License
Go to Setup and search for Installed Packages
In the Installed Packages section, click on Manage Licenses next to Subscription25
In the Licensed Users section, click Add Users
Add the users you want
Assign a Subscription25 Permission Set
Go to Setup and search for Users
Click on the user you want to assign a Subscription25 Permission Set to
Scroll down to the Permission Set Assignments section
Click Edit Assignments
Select any of the 2 S25 licenses and click on the Add arrow