[Grim_]

Alright, I think I may have found out.

pawn Код:

new business = PlayerInfo[playerid][pBizKey];

This variable holds a ID of a business key that the player has. If that value is not -1, then we know the player owns a business, by this check

pawn Код:

if(PlayerInfo[playerid][pBizKey] == -1)
{
   SendClientMessage(playerid, COLOR_GREY, "   You do not own a business.");
   return 1;
}

Now at this point, we know they own the business with the index inside the BizInfo array of business (which is equal to PlayerInfo[playerid][pBizKey]). So, with this check

pawn Код:

if(IsPlayerInRangeOfPoint(playerid,25.0,BizInfo[business][bInsideX],BizInfo[business][bInsideY],BizInfo[business][bInsideZ]))

We see whether or not they are within the certain range of the business they own.

So, what really checks if they have a business is the value held by PlayerInfo[playerid][pBizKey]. If it is a value other than -1, they own a business, which you can access the BizInfo array directly from with that index.