...Microsoft has a good track record of keeping so BugTracker.NET "Classic", which was born in 2001 and is still alive going into 2021, should be fine for the next few years.
So, about BugTracker.NET "Classic":
A web-based bug or issue tracker written using .NET 4.x Framework, ASP.NET, C#, and SQL Server (SQL Server Express too). Probably has all the features you need. Easy to setup. Power and flexibility when you need it. Learn more at http://ifdefined.com/bugtrackernet.html