I just revived 2 PurePitch Lager packs with manufacturing dates of Oct 2016 (WLP820) and Dec 2016 (WLP802) from the back of my fridge. Built them up in 3 stages 1.020 => 1.040 and => 1.040 again over 2-3 weeks. Both are cold crashing and ready for a 4 hour vitality starter on brew day (coming Sunday) before pitching. Also leaves me some for keeps/new starter.