Why do anti-spyware offer free download when you have to pay for it after you download it ?

Question

doesn't make since to me.

Answer 1

Not all do.  Download Avast, it's good and completely free.  A lot of people will tell you to get AVG, but avast is better.

Answer 2

The trick is they want you to try it ,if they have got none to try their product its useless thats how most of these anti-virus companies startup, they start offering it for free,then as its fame grows they include few restrictions like Number of days,How many times it might be used etc.....

The thing is most of them are run on donations from people like you and me,you can clearly see them asking you to donate inorder to pay for their server maintainence charges.