Concentrates will decarb over time. Basically the cannabinoid profile will change (become "stonier") and it will lose terpenes (taste). You can keep cannabis for a long time before it completely loses its psychoactive benefit, but I've noticed significant degradation (mostly in taste) after just a month and half (kept on parchment paper, room temp).
If you're going for longtime storage, I would get an airtight and lightproof container (AL foil and vac seal would work great) and throw it in the freezer.