Lifetime is printed by NGC on holders for coins that were minted prior to Alexander the Great's death in 323bc. the expanded grade description, as I currently understand it, is already included in the standard $55 grading tier, however, it isn't included when people grade coins in bulk or economy submissions (like mine was) . expanded grades are supposed to have attribution, weight, & sub-grades for Strike, Surface, & Style. when you get the expanded grade description, I think its possible to get a better overall grade (vs economy or bulk submission's basic net grade), because the strike, surface, and style grades are separately evaluated and the overall grade is more purely based on the level of wear on the coin.
https://www.ngccoin.com/specialty-services/ancient-coins/grading.aspx#3S
https://www.ngccoin.com/news/article/4532/Ancients-Economy-Tier/
Really jealous of the coin in your post by the way-- whether it's lifetime or posthumous(post 323bc), it's incredible! Do you have a photo of the obv handy? We might be able to attribute it to a likely mint location/date.