.htpasswd expiry implementation

[keak]

Hi all,
I am just wondering if anyone have had experience implementing a membership expiry with htpasswd. Say if a user signs up and I want to give him/her login for say 4 days, are there any good approaches to automating this expiry functionality in .htpasswd?

I can do this manually, but I can see it going out of control easily if there are many signups.

Any input is appreciated!