Unfortunately, it is not possible to transfer Demo accounts over to real ones.
In order to open a real account, firstly you will need to register a Client Area using the following link:
https://secure.tickmill.co.uk/trader/index.php?task=1050&referrer=stm or
https://secure.tickmill.com/trader/index.php?task=1050&referrer=tck
(please check whether your country is in the list).
Then you will need to upload documents into your Client Area for verification.
Documents are checked within 24 hours during working days. Once your documents and your Client Area are fully verified, you will be able to open a live account within your Client Area
Please contact your EAs provider to find out whether it is possible to connect them to another (live) account.