ESP8266 connecting keypad and lcd display
You can read the keypad using a single analog input (A0 in ESP8266) using this circuit:



When you press a key, some resistors are connected between Vcc and Ground. For each key, the total resistence is different, and the voltage at the input pin is different.

To read the keypad, you read the voltage at the input pin A0. You also have a table that associate the readings with keys. You search in the table for the nearest entry to the value you get. That's your key. 

Wire the circuit and make a little sketch to read the values for each key you press. That's how you construct your table.

The value at A0 will be a little different each time you read the pin. That's is normal. Don't expect a exact macht.