A new license can be installed in addition to a previous active license in order to add more licensed capacity or to replace an older license.
If you install a new license on or after its start date, it is activated. If there are multiple active licenses, the capacity of the licenses is aggregated.
You can install a license in advance of its start date. The license is then activated on its start date.
The procedure for installing a replacement license is the same as installing a first time license.