Link Aadhaar with the mobile number from your mobile phone, no need to visit nearest Airtel store. As per the government directive, verify your mobile number with Aadhaar is mandatory for all existing customers. The last date of linkage is 31-March-2018. Now verify your number sitting at home, just dial 14546 (tollfree). One Time Password (OTP) will be sent to your number registered in Aadhaar database.
If your Aadhaar belong to a different state than your mobile number, visit nearest Airtel store for postpaid connection otherwise (prepaid) visit your nearest retailer. Bio-metric verification is required separately for each mobile number. If you don't have Aadhaar card, request through the official site - https://uidai.gov.in. There is no fee for Aadhaar verification and re-verification.