Cannot buy Advanced Threat Protection Plan 1
I pay for and use Office 365 E3 through the Action Pack. I have successfully completed a trial of the Advanced Plan Protection Plan 1 add-on and now want to purchase it but there is no option to buy in the O365 portal.
Partner support says ATP Plan 1 can only be applied to a "base plan," meaning I'll have to discard the E3 licenses that I'm already paying for and pay for O365 again, just so I can add ATP Plan 1.
Meanwhile ATP Plan 2 is available to buy as an add-on, at 2.5 times the cost. That's not what my customers would want, so that's not what I want to add.
I thought the idea of in-house use was to allow the partner to familiarize themselves with the product so they could sell and support it. ATP should really be part of the IUP licenses, but if it's not, then at least let us buy it as an add-on.
Unfortunately it is correct that buying Add-Ons is only possible when there is a base plan with the same billing method - the problem you are facing does also apply to customer which have obtained licenses directly and want to get Add-Ons from a CSP Partner in CSP license channel or vice versa.
Usually you can resolve this by obtaining one eligible base plan for a short amount of time - e.g. obtain a single ExO Plan1, then add multiple Add-ons for ATP Plan1, then cancel the ExO plan1 license. So any additional costs can be limited and you do not have to discard the Action Pack licenses you already have.
For competency partners on Silver or Gold level there are competencies where you get E5 license which include ATP Plan2, but not for Action Pack.