You need to take them as soon as possible after the unprotected intercourse, preferable within 24 hours. After that they become less effective The e-pill is available over the counter, which means you can go straight to the pharmacy and get it without a doctor's prescription.
There are two types of emergency contraception pills however only one is currently available in Kenya. The available pill is progestogen-only (using the hormone levonorgestrel) generally referred to as P2. Another form of Emergency Contraception is the copper IUD however this needs to be put in by a medical provider.
There is no limit as to how many times you can use the emergency-pill in a year. However, the e-pill does have short-term side effects that mean it should not be used as a normal form of contraception, but only in case of emergency.