Head over to https://midnight.im/, register an account, head over to “User CP” & click “ACTIVATE KEY”, if any errors accure, please contact our support team. Press Download in the “User CP” section, run the .exe file and login with your https://midnight.im/ account, after so press “START IT NOW”. When the procedure is completed, you will be prompted to launch GTA 5.
Make certain that all anti-virus software and firewalls are turned off.
Windows reinstallation or hardware replacement both result in invalid HWIDs. In that scenario, you can resolve the problem by resetting your HWID on this page.
You should get in touch with Midnight support via their website if you have this problem.
INSERT is the standard hotkey for accessing the menu. To find that button on your keyboard, click this link.