PT Ultimate Perpetual (expired) to subscription - pay on monthly basis?

[peternincompoop]

Hi all,

I have a PT 12 Ultimate Perpetual license, with an expired support and upgrade plan.

I'm looking to move to the subscription model, and am given the 3 following options in my master account:

PT Ultimate - $79.99 1 year subscription, paid monthly
PT Ultimate - $59.99 1 year subscription Crossgrade, paid monthly
PT Ultimate - $599.99 1 year subscription Crossgrade, paid upfront

I take it that in this scenario the 'cross grade' option is discounted as I am surrendering my PT Perpetual license, correct?

...but does this mean I am unable to purchase PT Ultimate on a month-by-month basis? Am I only able to be locked into a full years subscription?

Hope you can help.

Thanks in advance!