If you mean that it is not visible in the Develop Module right side panel, click on one of the headers visible and you will get an option to reactivate it. The feature is available for all the panels Top, Bottom, Left and Right.
Thank you, but I'm talking about is not.
Should be in the middle of the photo is written as follows.
"Developer module is disabled."
"Please renew your membership to reactivate the Developer module."
I've got my membership
I did accidentally exit from the Help menu in Lightroom.
How can I access it again?
If you have a monthly or annual subscription you need to login via thew Creative Cloud application.