You might want to read the fine print of the CEX.IO Terms:
In case if it has been more than six (6) month since the User signed in with his/her Account or made the Funds deposit, CEX.IO has the right to qualify this Account as abandoned. In that case Storage fee will be applied to such Account with seven (7) days prior email notification to the User. CEX.IO will charge the Storage fee set forth herein. Abandoned Accounts with zero balances shall be deactivated.
Source: https://cex.io/terms