Benefits of a Premium account:

• +20% XP if all members of the squad have Premium.
  
• +10% XP for all members of the squad.
  
• +50% Credits awarded for combat and missions.
• +100% XP for all types of combat.
  
• +5% Free XP for all types of combat.
• +1 Materials Container per day, with an increased chance for Rare and Very Rare Materials.
  

XP lets you research new upgrades for the operator.

Free XP lets you upgrade any operator you want.

Materials are required for some operator upgrades and for skill research.