Nick has 3 keys; Kessler, Porter and Rennard. Rennard had one of the 4 royal keys but gave his family's key to Nick. We know Nick has the Porter key, though that is one we have yet to see on screen.
I have speculated that the seventh is in the hands of the wesen council and is in the spice shop.
The key Renard gave to Nick was Nicks own key; you know, the one Renard had stolen from Nick earlier in that same episode. He was returning what was rightfully nicks rather than adding to nicks collection.
Is it just the Austrian royal family that have the other four keys, because so far we haven't heard of or seen any other royal families, except perhaps Akira Kimura, who they hinted at working for the Japanese royal family..
Yes, we have only seen 2 keys the Kessler and Porter keys. Renard said the royal families had 4 of the remaining 5. That's the one I think the wesen council has and is in the Spice shop.
Renard did say families. I think Elizabeth Lascalles had help from another royal family, which demanded King Frederic's key in payment. In typical hexenbiest treachery Elizabeth kept the key. King Frederic wouldn't admit they'd lost the key and the other family wouldn't admit they either helped or didn't have the key. The key passed in Sean Renard's care. He announced to the resistance that he had a Grimm, but Nick would not be in Sean's corner without being entrusted with that key - probably now in Porter's cane that everyone knows Nick removed a key from. I admit this is speculation.
As for the keys themselves, the timeline suggests the 7 knights created the key maps in 1285. There's only one problem with this. Constantinople fell in 1204 to the Venetian and Latin Crusaders. That would make the knights rather old. Renard said in 600 years only another 3 keys were recovered after the first was forced to turn his key over. That would suggest in 1885 the royals shared out the keys and stopped trying to kill each other for them. They haven't stopped trying to find the other 3 killing as they went about their business. They've certainly known about the Kessler and Porter keys and are going after them. Renard did say thay an alliance formed between Nick and himself would lead to something historic. Some of that is speculative, too
I believe that those two skeletons with the jewels that Monroe saw in the catacombs may have contained the last two keys!:O Why else would they show them at some random scene unless of course, it meant something?