UK business visa not used yet. Is there a 3-month or void clause? [closed]

My UK business visa was obtained in October 2016 (for 2 years). I have to travel to the UK from July 28 to Aug 17, 2018 (within the 2-year period) on business (meetings, conference etc).

I am concerned that since I have not yet used my visa, the visa might be void (if memory serves, there used to be a 3-month or void). Is this a possibility? Is there anyway for me to check if the visa is in fact valid?