EVisa validity and re-application upon expiry

Dear Members,
Can anyone share details on valid timeframe and expiry of eVisa once issued.
I applied evisa online in first week of December 2018 and the eVisa was granted within 3-4 days and was showing validity of one month(valid until 8jan 2019).

However due to some reason I was unable to travel within specified time. I checked the validity online now and it doesn't say that the earlier granted eVisa is expired. However it does that visa will be granted for a month from date of first entry.

Is it that eVisa is valid only for a month from issued date and in all cases it it's not used in time, does it gets expired automatically and needs to be applied again.

Please share your experiences in this matter.
Thanks in Advance.

It is self explanatory.

The evisa has a validity date for "use".  If it is a month, then it means you need to enter within a month.  Once you enter, the days of stay are granted.  In other words, you can enter within a month and stay a month. 

If you don't enter within a month, the validity of visa expires and it must be re-applied for.

The Bahrain evisa system is not like Dubai (The AMER portal) or some other countries where they show live status and mark it as expired once time has passed.  Here, when you view the evisa, it shows you the details as at the date of approval - it doesn't get updated.  But yes, you cannot travel on it now.

Thanks Xtang for your quick reply.
It makes more sense now as you clarified that it's not real time update  once it gets expired.  There was a little confusion earlier as it was not showing as expired.
Got to apply again.

Thanks.