Use Google Maps when you are Offline

How Google Maps offline access works

You need to download the area that you want to work when you don't have mobile data or WIFI connection.You can download very large area.These can take up to 1.5 GB, depending on the area. There is a way to download this data to an SD card, though, which is a relief. Simply go to Menu > Offline Areas > Settings > Storage Preferences and switch “Device” to “SD card”.

These Maps expire after 30 days because maps are changing with time and google also improves quality of maps.
Steps:

1. Open the Google Maps.
2. Locate the area you want to download.
3. Tap on it to display more options.
4. Hit “Download”.
5. You can now pinch-to-zoom in and out, making the download area larger or smaller.
6. After making your selection, hit the “Download” button in the lower-right corner.