How would a third party app detect if MS word is installed

We are using some medical software made by E-mds and It looks to see if MS word is installed and if it isn’t some buttons are greyed out because they depend on word and it’s macro capabilities for form letters. The problem is that we have word installed on the machine and it was in fact installed before the E-mds software was. I have also learned that if I give the users administrator rights the problem goes away but I don’t want to do this. I have also tried giving them PowerUser right but this doesn’t solve the problem. My question is how do apps commonly determine if a app like MS word is installed. I would have guessed that it is by looking at the file extension but this is not the case.

Thanks for your help

Brandon Friesen