I'm pretty sure that's a premium service you pay a monthly fee to access. Definitely does not come standard with a BMW. You'll want to shut it off immediately to not incur extra charges to your BMW account.
The first 100 blinks per month are included with your subscription. Subsequent blinks are pay-as-you-go. Sign up now and we'll include an additional 30 days of right hand turn signal access, absolutely free. (Taxes and processing fees may still apply. Void where prohibited.)