It was a perk for token sale contributors back in August 2015 for a set amount of Bitcoin contributed.
Also premium members had the chance to access the Premium Merchant, again for a set contribution.
They may allow temporary Partner status in the future at a cost, I heard, but not sure when that will be.
Pretty mean to actual "Partners", when they invested they were told such a thing won't be possible.
P.s. I think it was a good idea to open "new partnerships" later on, to avoid excessive concentration of best cards. But I think they should have said it on start.