Asking something very basic

Working in US base company

As employee, I am entitled up to 20% discount if I want to buy their US shares

I have check their past 5 years performance, the share price is quite stable

Anything else I should check before I buy?

Did a basis calculation

For the past 5 years, average 7.8% increase per annum

Past 12 months, the increase is around 9%

Additional conditions

1. Must hold for 12 months before selling off. If resign or sell off before 12 months, will return the exact amount you put in
2. No voting right

Any other things I need to look into?