Submit button deactivation

I need help on how to deactivate a submit button after submission so as not to have multiple entries in my database. Again, i need help on code that will not allow anyone registering on my site to proceed to the next stage of registration without agreeing to my privacy statement just as it work on this board when one is trying to register without agreeing to the conditions of the board.

 

Hello,

<input type="submit" disabled="disabled" value="submit">

Jakomo