Related to Digital ocean and sensors

Digital ocean:

  1. Where is it showing my validity period?

Bolt wifi Module:

  1. Is it possible to connect multiple sensors to a single analog pin(A0)?

it is possible to connect multiple sensors to a single pin but you cant get the data at the same time you will have to use mux depending on the amount of sensors you want to connect and by the combination of the select pins of the mux you can get the data from the sensor you want. For example think you have four sensors which are connect to a mux for the first combination with you will have to gave from digital pins in this example for four sensor you have two select pins to select the first sensor it will be 00 for second it will be 10 and so on

you can cancel your account through control panel,under the settings tab.First, destroy any Droplets(Ubuntu server) active on your account, resolve any outstanding billing and then click “Deactivate Account.”

Can you show me video or photo of connection?

Take a look at this,
Even Nodemcu has single analog pin - https://www.instructables.com/id/Multiple-Analog-Inputs-on-Only-One-Analoge-Pin/