Upgraded from Adobe After Effects 2015, to 2018 and I have to buy a new liscence?

I am on a student plan, which is supposed to give me all of the apps on the creative cloud for 20$ a month, however this past weekend when I updated my After Effects, it said that I was on a free trial? Is this normal? Is there a way I can convert back to 2015 version to get my liscence back? How would I go about fixing this?