Dear aspirant
Any certificate whether it be caste or income or nativity until unless it says that it is permanent certificate the validity of such will be only for 6 months.
So your caste certificate which you have taken on the year 2018 is not valid for this years eamcet counselling. Please get another caste certificate or renew it as soon as possible before the counselling
https://www.google.com/amp/s/engineering.careers360.com/articles/ap-eamcet-counselling/amp