We're primarily developers - not software manufacturers - but we occasionally sell a couple of products we've written.
The revenue we generate with them can't justify a good attorney, so several years ago we looked at End User License Agreements of some of the well-heeled software companies we deal with and adapted the sections that made sense to us into a document. That took a day or so of our time.
They primarily limit your liability, limit the usage of the software to the buyer, etc.
We include the EULA document we concocted in the installation package and require an ACCEPT as part of the installation package. We make sure that the end user participates in the installation.
Foolproof? No.
But it's better than nothing.