Hi Jaymo,
If you originally registered your copy there is a way, go here https://www.serif.com/en-us/legacy/product-keys/ .
One thing you need to know, since MoviePlus is a legacy product and no longer supported a new installation is no longer fully functional. Serif has turned off the unlock sever for licensed codecs specifically MP4, VOB. Unfortunately, I have to assume that when we purchased the product we did not get a license which is a real problem with me. For me this is BS!!!
It would have been a welcome gesture by Serif if they would give us the option to purchase the licenses when the decision was made to abandon the product.
I discovered this after installing MoviePlus on a new PC several weeks ago. At this point I find only WMV, MOV, MPG and AVI (not using an MP4) codec functional.
As a side note, I suggested to Serif that they should resurrect MoviePlus under the Affinity brand. There response in essence was ' not going to happen anytime soon '. My understanding the reason for this is the original development team left the company.
My solution to the problem was to purchase Adobe Premier & Photoshop Elements.
Hope this helps.
Best regards...