In adding Registration Date Column on Users Page in Admin Area, the first thing you need to do is to install and activate the Admin Columns plugin. On activation, you need to visit Settings > Admin Columns to configure the plugin. Below the admin columns tab, click on users and then click on add column button. Then select “Registered” in the Type drop down menu and click on store updates button. You will be able to visit the users’ screen where you will see a new column labelled “Registered” showing the date when a user registered on your WordPress site. In order to show Registration Date Field in User Profile, you will need to upload a custom plugin to your website. Simply create a new file on your computer using a text editor like Notepad and save it as membersince.php on your desktop. Followed by opening the file and paste the code inside it. Save your file and then upload it to your WordPress site. That’s all, go to your WordPress plugins page and activate this plugin on your website. Authenticate everything that is working by editing a user profile on in your WordPress admin area, and you will able to view the user registration date.
To copy the code and paste it on your file as mention above and/or for further information about the plugin, kindly check at Show User Registration Date in WordPress.