Q: install apps from different region

You may only buy things from the store for the country in which you are a legal resident, not a tourist.

Changing the country for your account for a free app in a country you are visiting will cause many issues for your account. Primarily, your account will forget your past purchases in your home county's store.

You need your Purchases list to be alerted to future updates to Apple & 3rd party apps and to redownload content easily. It isn't advised to change countries frivilously.

To change countries, go into your iTunes/Mac App Store account details. After changing the country you will be required to provide a credit card issued by a bank in the new country that has a verifiable billing address in that country.

Change the country of your iTunes Store, App Store, iBooks Store, and Mac App Store account - Apple Support