Update number-lookup.md

Author: ericasp16

articles/communication-services/quickstarts/telephony/number-lookup.md

@@ -37,6 +37,7 @@ zone_pivot_groups: acs-js-csharp-java-python
 
 Common questions and issues:
 
+- When adding or editing environment variables your changes may not take effect in programs that are already running. If you notice your environment variables are not working as expected, try closing and reopening any programs you are using to run and edit code.
 - The data returned by this endpoint is subject to various international laws and regulations, therefore the accuracy of the results depends on several factors. These factors include whether the number was ported, the country code, and the approval status of the caller. Based on these factors, operator information may not be available for some phone numbers or may reflect the original operator of the phone number, not the current operator.
 
 ## Next steps