- Ability to synchronize with the Anki server
- Ability to review
Any price is OK.
No, there is currently no such app. The only solution is to open your web browser and use Anki's web interface called AnkiWeb:
Beware, several Windows Phone apps with "anki" in their names are getting money from unsuspecting users but are actually not compatible with Anki. Example:
I bought AnkiApp thinking it was anki's attempt at an app for windows phone... I think I've been duped into paying $5 for a broken ass app.
A few reviews for AnkiApp: "This is a knockoff of the real thing." "Not actual anki, can't import from the desktop version." "It's not Anki."
There is also an app called Anki FlashCards WP but it only embeds AnkiWeb (plus probably some advertisements and spyware, see the creepy permissions the app asks for) so better use AnkiWeb directly.
Windows 10 might be able to run reworked Android apps, so there is hope, but it has not been tested yet.