[Plugin: S2Membership] Fixed EOT for Re-occurring payments

I have been searching the internet and S2Membership’s website far and wide for an answer to this, and contacting their technical support has rendered no response.

I have a client that is using S2Membership Pro and Paypal Pro forms.

They are offering a special membership for the summer months. They want this to re-occur monthly, however they want the membership to be terminated October 31, 2015 no matter what. However, the user needs to be billed monthly until then.

I found this article on the S2membership site-
https://s2member.com/kb-article/how-do-you-create-a-subscription-that-ends-on-a-fixed-date/

This shows how to add a fixed EOT using some PHP, but this only seems to work for the “Buy Now” reoccurring option. Upon switching to a monthly re-occuring option, I get an error saying the following:

“Invalid form configuration. Invalid “rt, rp, rr” attributes. The “rt” (Regular Term) attribute is “M”, “rp” (Regular Period) > 12, and “rr” is not “BN” (Buy Now).”

Does anyone know how to make this work for a re-occuring payment? Or how to go about contacting the developers of this plugin so my clients who are paying for the Pro version can actually get a response? Please help!

I know that you can set the EOT after a user has been created, but this seems like a lot of work for my client to do. I would hope there is a way to automate this.