Got this from the summary tothe Season 7 episode "Im gonna be like you, Dad:
With his college graduation less than four months away, Alan and Amy agree to let Eric work at their wilderness store to gain some real-world working experience. Surprisingly, Eric does great at the store and is really comfortable dealing with customers. In an attempt to get Eric to continue working there, Alan informs his family that he is changing the store's name to Matthews & Son Wilderness.
Although he claims that he is just proud of his son for doing well, Amy accuses Alan of not having any faith in his own son to pursuewhatever it is that he wants to do. Alan then reveals that he is just worried about Eric being confused like Jack and Rachelwho are also graduating soon
So, from that it's clear they were seniors, and Im pretty sure they did graduate before the finale (obviously not shown)