Could you add a reminder, such as an email, sent out *before* a Pro account expires? Every single time it does, I keep wondering why the Android client hangs on sync.

This paragraph is semi-off topic for a feature request, but:
By the way, there seems to a bug in the Android client related to this, as hinted to above. When I tried to manually sync this morning, it just kept hanging; the sync icon spinning for minutes. Eventually, I exited the app, killed it with the Android task switcher, and tried syncing again. This time, it told me immediately that my Pro account had expired.
So, I upgraded to Pro again (via my computer), and a few minutes later tried to sync again, saying "not now" to upgrading to Pro, as I'd already done so. The sync again hanged for several minutes. After rebooting my phone, I'm finally back to normal.

... and I just now noticed there are *two* doit.im apps for Android, and that I've been using the older one (3.9.x), which claims it is the latest version. I'm fairly sure I never got any kind of notification telling me to upgrade, and so when both the play store *and* the app it told me I have the latest version, I obviously trusted them!
The only reason I ever noticed is that I saw "4.1 for Android" in the sidebar on this current page, so I checked which version I had.

So, in short:

1) Please add a reminder where a Pro subscription is about to expire, instead of just catching people off guard when they may rely on the sync working. Personally I'd prefer an email, sent about 1 week prior.
2) The older Android app (not sure about the new) has a bug where an expired Pro account hangs the sync with no message, until a restart.
3) I'm almost positive I did not get any sort of notification that the app I've been using is outdated and should be switched for a separate one in the play store, which is obviously rather terrible.

Regards,
Thomas