diff --git a/api.bs b/api.bs
index 321390f..e99375f 100644
--- a/api.bs
+++ b/api.bs
@@ -860,7 +860,7 @@ The [=impression store=] is a [=set=] of [=impression|impressions=]:
     or `undefined` if the API was invoked by the [=impression site=].
 <dfn>Conversion Sites</dfn>: The [=set=] of [=conversion sites=] that were passed to <a>saveImpression()</a>.
 <dfn>Timestamp</dfn>: The time at which <a>saveImpression()</a> was called.
-<dfn>Lifetime</dfn>: The number of days an [=/impression=] remains eligible for attribution, either from the call to <a>saveImpression()</a>, or a [=/user agent=]-defined limit.
+<dfn>Lifetime</dfn>: The [=duration=] an [=/impression=] remains eligible for attribution, either from the call to <a>saveImpression()</a>, or a [=/user agent=]-defined limit.
 <dfn>Histogram Index</dfn>: The histogram index passed to <a>saveImpression()</a>.
 </pre>
 </div>
@@ -1414,6 +1414,9 @@ To perform <dfn>common matching logic</dfn>, given
 1.  [=set/iterate|For each=] |impression| in the [=impression store=] for the |epoch|:
 <!-- TODO: Clarify "for the |epoch|" -->
 
+    1.  If |now| is after |impression|'s [=impression/timestamp=] plus |impression|'s
+        [=impression/lifetime=], [=iteration/continue=].
+
     1.  If |now| - |lookbackDays| is after |impression|'s [=impression/timestamp=],
         [=iteration/continue=].