XE2+ Plus Pack is sold as a lifetime license. Once purchased there is no more to pay.

Plus Pack purchase options
XE2+ Plus Pack100.00 EUR
Purchase for Delphi XE2, XE3, XE4, XE5, XE6, XE7, XE8, DX10 Seattle, DX10.1 Berlin support, DX10.2 Tokyo support

NOTE: XE2 and above licenses are compatible. You only need to purchase one product (XE2 or above) and the license information works for other IDE versions, excluding Delphi XE.

The Delphi XE license is free now. Refer to my blog post on the topic.