Why the running applications in my phone often automatically turn off?

Just like what the title said, the running applications in my Huawei phone often automatically turn off. It likely to be a software problem or hardware problem? My phone has been use for more than one year. what can I do to make it better? Thank you for you attention.

Model: Huawei honor 6

crwdns2893858:0crwdne2893858:0 crwdns2893862:0crwdne2893862:0


crwdns2889612:0crwdne2889612:0 0