If you are receiving the email alerts "License acquire failed" for a particular site, check the email content for the details of the reason for the failure.
1. Site token doesnt match: This means either the same site_id is used in another setup or the server is sending an old token that doesnt match with the token licensing server has.
Do not use same site_id in multiple servers which are not part of the same deployment.
If the error continues to occur, token can be reset from licensing portal(www.iraware.com).