All of these UV cure resins have a 'shelf life'. Unfortunately I think that the only one that carries the appropriate information is Liquid Glass UV cure resin from Harvey Angling. This has a 3 year shelf life.
I had similar problems with tackiness with both the Harvey Angling and Bug Bond Lite products.
I bought some Solarez products and have found the UV Thin Hard formula to be excellent, it cures very quickly with no tack and if left in daylight for a couple of days sets rock hard. Normal cure time is stated as 15 seconds either by UV torch or placing in direct sunlight.
There are three products in the range, UV Thin Hard, Uv F-L-E-X formula and UV Thick Hard. The Thick hard is a bit too thick for small flies but would probably be good for larger streamers,fry imitations and salmon flies. I haven't found a use yet for the flexible formula but it would probably be good at repairing waders etc. The Thin is excellent on smaller fly heads and epoxy style buzzers.
All 3 come in 5 gram tubes with a small nozzle making it very easy to use. These tubes last a long time.
The product is made in the States by Wahoo. I have only found it for sale on e bay, The cheapest company is in France but their service is very good and so are their prices.
Hope this helps.