In Salesforce, how Lightning user permission can be assigned?

If your org has purchased Lightning Console permission set licenses, you can assign the licenses to users with Salesforce Platform licenses to add access to Lightning console apps.
REQUIRED EDITIONS AND USER PERMISSIONS
Available in: Lightning Experience
Available for an extra cost in: Essentials, Professional, Enterprise, Performance, Unlimited, and Developer Editions
USER PERMISSIONS NEEDED
To create permission sets: Manage Profiles and Permission Sets
To assign permission sets: Assign Permission Sets
Each Salesforce Platform license user needs a Lightning Console permission set license to use Lightning console apps. Creating a Lightning Console permission set and assigning it to a user auto-assigns the Lightning Console permission set license to that user.