Static or dynamic IP?

I just started few days ago the development of an application based on Wemos D1 mini, remotely controlled by iOS device.
Everything works fine when the smartphone uses a wifi network (same network used by Wemos) but…as soon as the phone is outside wifi coverage (or wifi disabled on the phone)…no way to get it working (strange things happen!).
I surfed a little bit in the forum and I discovered that somebody else already experienced a similar problem and I had the idea to set the blynk server IP address instead of It works fine!
The problem is solved…until maintains the same IP address!
The question now is: can I rely on this work around solution or the has a dynamic IP address?
thank for your

@pielle Hello. Right now IP is static. However this will be changed very soon when we will introduce Geo DNS fix.