How to bind your MT4/MT5 EA to a specific account number

You want your EA to run on your client's account, and refuse to run anywhere else. That's account binding, and it's the most common first line of protection EA sellers reach for. Here's exactly how to do it in both MQL4 and MQL5, and an honest look at how far it actually gets you.

01 / The ideaCheck the account number on startup

Every MetaTrader account has a unique login number. Your EA can read it at runtime and compare it to a number you've authorized. If they don't match, the EA stops before it places a single trade. Simple, and it works as a first gate.

The function differs slightly between platforms. In MQL4 it's AccountNumber(); in MQL5 it's AccountInfoInteger(ACCOUNT_LOGIN).

02 / The codeMQL4 and MQL5, ready to paste

MQL4

// --- Account binding (MQL4) ---
long AllowedAccount = 123456;  // your client's account number

int OnInit()
{
   if(AccountNumber() != AllowedAccount)
   {
      Alert("This EA is not licensed for this account.");
      return(INIT_FAILED);
   }
   return(INIT_SUCCEEDED);
}

MQL5

// --- Account binding (MQL5) ---
long AllowedAccount = 123456;  // your client's account number

int OnInit()
{
   if(AccountInfoInteger(ACCOUNT_LOGIN) != AllowedAccount)
   {
      Alert("This EA is not licensed for this account.");
      return(INIT_FAILED);
   }
   return(INIT_SUCCEEDED);
}

Drop that into your EA, compile, and the robot will only initialize on the account you specified. For a single hand-delivered copy, that's a reasonable start.

03 / The catchWhy this isn't real protection

Here's the part most tutorials leave out, and it's the part that actually matters once you're selling to more than one person.

It gets worse with volume. Hardcoding AllowedAccount means you compile a separate copy of your EA for every single buyer. Ten customers, ten builds. Someone wants to switch brokers? Recompile and re-send. A trial expires? There's no expiry, you'd have to remember and manually chase it. It doesn't scale, and it doesn't hold.

04 / What actually holdsMove the check off the file

The fix is the same principle behind every serious EA license system: don't let the EA decide whether it's allowed to run, have it ask a server. Instead of a hardcoded number baked into the file, the EA sends the account number and a license key to a server you control, and the server answers.

The technical move in MQL is the same OnInit hook you saw above, except instead of comparing to a hardcoded number, the EA makes a WebRequest to a validation server and acts on the response. Make the server return a value the EA actually needs to trade, not just true or false, so deleting the check breaks the EA instead of freeing it.

Use the hardcoded version above if you're handing one EA to one trusted person. The moment you're selling to strangers, move the check off the file. That's the difference between a lock and a speed bump.