How to make an NPC give ONLY ONE potion?

How do I make it so that an NPC gives only one potion only-because right now, each time you talk to him, he gives a free potion (not good). I am using RPG maker 2k.

at the end use "turn self switch A on"
new event page click teh box for self switch A.

self switches don't exist in 2k. You can use regular switches though

wait-so in events, I click on change switch. Then what do I do?

I recommend you switch to 2k3 or even XP version of rpg maker. it will be alot better and there is more people using it on this forum so help is always easy to get.

http://crankeye.com/index.php?page=downloads

You have to make a second page in the event which is conditioned on the switch you turn on after the potion is given. Essentially what that will do is make it so that the second page in the event will only when that specific switch is ON. Since you don't turn that switch on until after you are given the potion, the first page will run the first time you activate that event. But, since the switch is ON now, the second page will run each subsequent time you talk to the NPC.

And yeah, you really should switch, as there are a lot of good tutorials on XP and 2k3 and a lot of people use them. If you don't switch, you should still read the tutorials, because there are a lot of common features. So far, every question about eventing you've asked is answered in at least one of the tutorials.