Error

I dragged the newsletter widget to the sidebar and tried to subscribe to myself but get this: Fatal error: Allowed memory size of 41943040 bytes exhausted (tried to allocate 78 bytes) in /home/wowmusth/public_html/wp-includes/pomo/mo.php on line 230

Can you help me? Which information of the documentation I missed?

Thank you.

https://wordpress.org/plugins/newsletter/