[2 keys i will use the first to get 1 year can i use the second to extend it to two years?]

Also, in addition to what nexon indicates in the post above this post,

 

Did you buy two one year keys, or one key for two devices for one year? 

 

I will buy a 1 user for 4 devices for 1 year 

What does that mean ? 

[2 keys i will use the first to get 1 year can i use the second to extend it to two years?]

hi guys i just if i bought 2 keys i will use the first to get 1 year 
can i use the second to extend it to two years?
thanks in advance