Complete Passholder Quests and activities to earn Passholder XP. Earning Passholder XP increases your season Tier level and earn more rewards.
 
Upgrade at any time during the season to Passholder Gold or Platinum to instantly collect all gold or platinum tier rewards that you have unlocked.
 
This means if you have reached Tier 15 on the Free track, upgrading to Gold or Platinum will instantly award you all Gold/Platinum rewards from Tier 2 to 15, as well as access to the Gold Quests!