Nexus 5 won't get N, but how long will it get 6.x sec updates?

Anyone with more detailed info than this:
http://ift.tt/28LAqsO

Quote:

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Nexus devices get security patches for at least 3 years from when the device first became available, or at least 18 months from when the Google Store last sold the device, whichever is longer.

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Is the last sec update patch August 2016 or Sept. or Oct.?