The season pass runs per wipe and has 30 tiers with real item rewards. You earn XP for almost everything: player kills, raids, captures, bounties, missions, events, crates, animals and gathering. During northern lights all XP counts double.
The free track is for everyone. The premium season pass unlocks a second reward track – in the Radcoin shop for 1.000 Radcoins or in the Tebex store. Claim reached tiers in the "Season pass" tab.