visitor visa for MIL....

[carpdiem]

My mother in law got her visitor visa multiple for 5 years in Pakistan. She is not planning to come right now. I want to ask is there a specific timeperiod in which she HAS to come and if she doesnt the visa would get invalidated? like 6 months or something? or can she come any time in next 5 years?
Please help!

Thanks,

Sanna

[knowledgeable]

Anytime in 5 years

.