eM Client UWP: perpetual license?

Is it possible to subscribe a Perpetual License with the eM Client UWP version from MS Store?
I see only a monthly subscription option…

No, unfortunately not. The MS Store version is a monthly subscription.

However, the version which you can download from our website, uses a license which is a one-off payment, and is yours to use for life at no additional cost. There are two Pro license types; a single version license (so for version 9 only) or a lifetime upgrades version (all current and future versions).