Due to Republic Act No. 11934, or the SIM Card Registration Act, requiring all Filipinos to register their SIM cards, everyone must register their sim otherwise it will expire 6 months after purchase. Either you are Globe, Smart / TNT subscribers, here is the link where you can register.
https://www.globe.com.ph/register-sim-card.html#gref or in the Globe App
Smart / TNT
https://simreg.smart.com.ph/ or in the Smart App
Register via the DITO App
Note: Take note of the registration code upon successful registration, that might be handy should be needed in the future.