I'm writing bug reports by using Bug Tracker 2.9.1 version but after 50 reports, I need to pay money in order to continue using it. Are there any programs for bug reports which I can download for free?
Mozilla's Bugzilla may be a good option. As any tool, it has some learning curve.
If your needs are simpler, you may not need a specific tool. You can write forms on a text processor or JSON files (which can be easilly processed, by the way).
There are many tools for reporting bugs. It depends what tool your team wants to use, and which features are important for your team. Who will be using it? Web-based or desktop? Integrated with version control? Any preferred dev language for possible customization?
You (or your sysadmin) can install something like Trac or Bugzilla. Simplest solution is just use shared GoogleDoc spreadsheet.
Few seconds of googling ("free online hosted bug tracker") gave me bugheaven.com, which hosts bugzilla free for 5 users. There are dozens more.
These are some really good bug reporting tools you can have a look at-:
i) Bugzilla -: Detail Tabular & graphical report, Time Tracking, Email Notifications etc.
ii) Lean Testing -: Browser extensions for Chrome, Safari, and Firefox that allows to take screenshots of and report bugs on the spot, Email notifications, In-app bug reporting in mobile apps allows to annotate screenshots from phone
iii) Bugsnag -: error monitoring, Unlimited monitored apps, Automatic Error diagnostics, Email Alerts, User interaction breadcrumbs. I personally like Bugsnag for its advanced features like automatic error diagnostics & User interaction breadcrumbs.