I have a basic email template I start with, and then modify based on the customer. Here's some of the basics of it.
***
An intro paragraph specific to the customer always goes first, and then the following...
In case you are not familiar with 100c, here is some information about it:
https://www.sage.com/en-us/products/sage-100/
You can also review the 100c brochure here:
https://www.dropbox.com/s/b0237itd1l00er0/Sage%20100c%20Brochure.pdf?dl=0
The primary difference between your perpetual license and the subscription is that you must keep your subscription current/active or the product will become read-only. You have been renewing your business care plan consistently every year that I do not believe this is a concern. The only other caveat to the subscription is that you must pay Sage directly by credit card or bank debit (ACH).
Let us know if you have any questions or would like to discuss. If you would like to move forward with the subscription, I will have Holly send you a link via DocuSign that can be completed electronically.
***
Again, depending on the customer, I might be more detailed instead so matter of fact. For customers who always renew their business care plan, it seems to make perfect sense to migrate to 100c and be done with it. For those who do not, it is much more difficult sell.