I have done registration of jee mains in january but i am going to attempt in may so again I have to deo registration?

Dear aspirant,

If you have applied for the jee mains exam in February then it is only for that particular session but you need to apply again for the rest of the sessions. So you need to apply again by paying a fees of 650.

For more information check out the link given below-

https://engineering.careers360.com/articles/jee-main-eligibility-criteria

Dear student,
If you have registered for February session in January, then that will be considered only for the February session, to appear for other sessions you need to apply for them when the application window opens. Keep in mind that for the session you have registered, if you do not appear for it, it will not affect the other sessions but you need to apply again for the other ones and pay the registration fee again. The application window for may session will most probably open in the month of April so keep an eye on the official website.