Compare archive length with free trial

If archive exists raise error as free trial should be disabled.
Error is added to csp config to propagate adapter error to product.

csp_billing_adapter/adapter.py

@@ -252,6 +252,21 @@ def event_loop_handler(
         add_usage_record(usage, cache, config.billing_interval)
         csp_config['base_product'] = usage.get('base_product', '')
 
+    try:
+        archive = retry_on_exception(
+            functools.partial(
+                hook.get_metering_archive,
+                config=config,
+            ),
+            logger=log,
+            func_name='hook.get_metering_archive'
+        )
+    except Exception:
+        archive = None
+
+    if archive is None:
+        archive = []
+
     log.debug(
         "Now: %s, Next Reporting Time: %s, Next Bill Time: %s",
         date_to_string(now),
@@ -262,7 +277,15 @@ def event_loop_handler(
     trial_remaining = cache.get('trial_remaining', 0)
 
     if now >= string_to_date(cache['next_bill_time']):
-        if trial_remaining > 0:
+        if trial_remaining > 0 and len(archive) > 0:
+            msg = (
+                'Free trial is active but archive contains metering history. '
+                'Usage will be billed for the previous cycle.'
+            )
+            log.warning(msg)
+            csp_config['errors'].append(msg)
+
+        if trial_remaining > 0 and len(archive) == 0:
             log.info('Attempt a free trial billing cycle update')
             process_metering(
                 hook,