I'm looking at adobe.com in the wayback machine for 2015 and while the CSS is missing, the <select> dropdown right on the /plans page include:

* Annual plan, paid monthly

* Annual plan, prepaid

* Monthly plan

And this is how I remember it back when, I signed up for a short gig where I only needed it for 3 months and went for the monthly plan, and then when the gig became a contract I switched to the annual paid monthly.

I think what changed is now the plans page says upfront "early termination fees apply" right next to the price.