Two Subscriptions - how to?

I have upgraded 2.X to 3.X but have it on 3 machines already and would like it on a fourth (and possibly more in the future). Is it possible to buy another 3 PC license using the same account/email?

I am using it for imaging on one remote observatory and one roll-off at home and would like to use it for planning on two separate machines at home plus maybe a laptop as required.

Thanks