You will be asked to log in to your account when you first start Acronis True Image (the software remembers your login, so you will not need to re-enter it every time). When you provide your account's credentials, the software will automatically activate the serial number registered in your account, in this case you do not need to type the serial number manually. Signing in is necessary to access Acronis Cloud and use all cloud-based features like backing up your computer and mobile devices to cloud, archiving data to cloud, and backing up social network accounts.