Is lying to my friend about the amount of Qur'an I have memorized, in order to encourage her to continue memorizing, considered permissible lying?

Lying is forbidden and is not permitted except in cases of necessity or a need deemed legitimate by Islamic law. The desired objective can be achieved without lying by using 'ma'arid' (euphemisms or ambiguous statements). This is when a person says something intending one meaning, while its outward appearance suggests something else. An example of this is Abu Bakr's statement about the Prophet, peace and blessings be upon him: "He is a guide who guides me," meaning he guides him to the right path, while appearing to mean he guides him on the road.