Hi,
There could be two answers to your query.

If you are talking about that you got yourself registered for AIBE exam that was to be held in 2017 then on the basis of that one, you won't be allowed to appear in the AIBE-XIII instead you would have to complete the Registration for AIBE-XIII.

If you are saying that you got registered as an Advocate on a State Bar Council Roll in year 2017 then you are eligible for the AIBE which will be held on Dec 23, 2018.

See BCI Clarification

I hope it helps!

AIBE is an Entrance exam conducted at National level by the Bar Council of India. The exam aims to test the ability of advocates to practice law as a profession in India. In 2017 you made the registation but didn't appear for AIBE Exam then you can not aply for December 2018 exam, You need to do the registration in the same year to appear the exam. You can check the complete information with the given below link.

https://law.careers360.com/articles/aibe

Good Luck!