A subscription can be registered with AppLife Manager via the command line using the RegisterNewServer.exe in the AppLife Manager install directory (%ProgramFiles(x86)%\AppLife Manager)
The command line will require UAC elevation.
Usage:
RegisterNewServer.exe <SubscriptionID> <ClientAccessKey> [<disableAppApprovals>]
<SubscriptionId> The subscription Id or the Publisher Code to be registered. (Required)
<ClientAccessKey> The client access key to be registered. (Required)
<disableAppApprovals> true or false. Optional and defaults to false. Set to true if new applications will not require administrative approval before applying updates through AppLife Manager.