There may be a way to use a commercial registration page add-on like Datasprings and UcanUse sell, but really, you have to be able to upgrade your DNN portal system if you're serious about using it. It's like upgrading your operating system or any other software. You can of course leave it where it is, but then you have to use it as it is... with all bugs and security issues that it had at the time.

The first step before doing an upgrade is also an extremely important generall DNN operational requirement - That you are able to make a full site backup, with file system and database, and restore it. If you can't do a backup and restore now, then you're already asking for real trouble. However, if you can do that, then carrying out an upgrade is not a major problem either.

Or, you'll have to get someone to do it... but if you're in here asking stuff then you're all ready in at the deep end so you may as well look into it.

So... first sort out the ability to backup and restore. Then have a read of one of the many upgrade guides around. I haven't saved any of the links, but Sebastian and Mitchell and others here are always pointing to them.

Rob