I think that if you make your choices list a value=>label list, this should work: https://wordpress.stackexchange.com/a/11454/20807
Instead of your current list,
1 : Ultimate Plus
2 : Ultimate
3 : Professional
4 : Commercial
5 : Business
6 : Free
It can also be in the order that you currently have
6 : Free
5 : Business
4 : Commercial
3 : Professional
2 : Ultimate
1 : Ultimate Plus
Then, the meta_key / orderby combo should get you where you want.
More info about ACF’s Select field type: http://www.advancedcustomfields.com/resources/select/