The company I work for recently purchased some third party libraries from a very well-known, established vendor. There is some fear among management that the possibility exists that our license to use the software could be revoked somehow. The example I'm hearing is of something like a patent issue; i.e. the company we purchased the libraries from could be sued and legally lose the ability to distribute and provide the libraries. The big fear is that we get some sort of notice that we have to cease usage of the libraries entirely, and have some small time period to do so.

As a result of this fear, our ability to use these libraries (which the company has spent money on...) is being limited, at the cost of many hours worth of development time. Specifically, we're having to develop lots of the features that the library already incorporates.

Should we be limiting ourselves in this way? Is it possible for the perpetual license granted to us by the third party to be revoked in the case of something like a patent issue, and are there any examples of something like this happening? Most importantly, if this is something to legitimately be concerned about, how do people ever go about taking advantage third-party software while preparing for the possibility of losing that capability entirely?

P.S. - I understand that this will venture into legal knowledge, and that none of the answers provided can be construed as legal advice in any fashion.