Nope, absolutely not a parallel process. You should keep that type of event to an absolute minimum because of lag issues and the way it can interfere with other events.
Make a new Control Switch. For the sake of this example, we will say it is switch 59. Name it with something you will recognise so that you know what it is for, and so that you don't accidentally use that switch for something else. It could be something like Key 1 Found
Put an event where you want the key to appear. Have nothing at all on the first page. Set it to 'Below Characters'.
Make a new page and set the condition (top left) to Switch 59 is ON
In the graphic section, put an image of the key.
Set it to Same as characters
In the command section, put Change Item command so that one key is added to the player's inventory.
Have a command Control Self Switch A ON
Make a third page with nothing on it except the condition Self Switch A ON. Make it 'Below characters'
On your NPC.
Text (whatever you want the NPC to say).
Command Control Switch 59 ON
The key now appears
The player interacts with it. That triggers the command to give the player the key and turns self switch A On.
The event now moves on to page 3 and the key seems to 'disappear'.
The main problem I see with this is putting the key event on a tile that you can be sure the player will not be standing on. This is a problem for 2 reasons.
If it is immediately in front of the NPC, as you said in your post, it won't be possible to interact with the NPC because the player cannot trigger an event while standing on another. Or, at least in Ace that was the case, and I don't think it changed with MV.
It also means that the player can't see the key because they are standing on it. Even if it's a tile or two back from the NPC, if you are showing followers, one of them might be standing on it so you still couldn't see it because their sprite would be in the way.
You will, therefore, have to have that event in some plausible place where the player and followers cannot be standing on it.
As you seem to be a new user, could I strongly recommend that you pause and look at Andar's compilation of
info for new users. Among the many helpful things there are two playable tutorials, one for Event Commands and one for Switches and Variables. If you play through these you will have a solid foundation in 2 essential elements of making a game. Spending a bit of time on it now will save you a huge amount of time and frustration in the future. Playable tutorials will teach you a lot more than just watching video tutorials as you learn more with an interactive tutorial. You can also open up the tutorials in editor mode to look at the way each thing is done and so can see for yourself have something is carried out.
