With /check command in your membership bot you can see your user summary:
Email (if provided)
Active plan (if any)
Resources access status
Here's how it looks:
To use this command, you'll need the user ID (this is the Telegram user ID actually).
Here's how you can get these IDs:
in payment/subscription notifications;
in List users / List clients / Export data (CSV) commands of Telegram bot menu;
by forwarding a message from the user to @userinfobot in Telegram
in SuchChat web interface.
You can also ask the user to launch @userinfobot in Telegram and it will reply with the ID.