Is my modem locked to Plusnet?

[#1]

I have a BT OpenReach Fibre VDSL2 Modem - type 061513 supplied by Plusnet, with a manufacturer date 9/2013.

Is this likely to be locked to Plusnet. I was wondering if I can give it to someone to make use of, or is the only option recycling it at the tip?

[#2]

If you wish to return it to Plusnet, rather than sending it to the tip, see https://www.plus.net/help/broadband/returns/

[#3]

I have a BT OpenReach Fibre VDSL2 Modem 

Openreach modems were never locked to an ISP. However, most people these days prefer a combined modem/router rather than two separate boxes. There's still some for sale on a well known auction site though, I'd try putting it on there