According to document below, starting in Ansible Tower 3.8.1, we can apply multiple subscriptions to a single installation by adding multiple subscriptions of the same type to a manifest file and uploading them.
However, when this occurs, the Tower GUI does not update the future dated Expiry Date on the license and only shows the Expiry Date of the current subscription and it looks like the updated manifest file has not been applied.
However, it is supporsed to require to update the GUI in a future release of Ansible Tower to better show any future listed subscriptions loaded into the system.
Ansible Tower >= 3.8.1
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